add notices to those who wish for a greater challenge

We add the following level-3 header to help people identify text
they may wish to skip if they wish for a greater challenge:

```
```

After that notice we add:

```
**If you want a greater challenge, don't read any further**:
just try to understand the program via the source.

If you get stuck, come back and read below for additional hints and information.
```

And sometimes follow with:

```
```

Or sometimes follow with:

```
```

Where the alt code impacts a "greater challenge", we add instead:

```
**If you want a greater challenge, don't read any further**:
just try to understand the program without looking at the Alternate code.

If you get stuck, come back and look at the Alternate code.
```

And where a given command impacts a "greater challenge", we add instead:

```
**If you want a greater challenge, don't read any further**:
just try to understand the program without running the command below.

If you get stuck, come back and run the following command:
```

Perform `make www` to perform the above and test under macOS.

1994/horton/README.md

@@ -68,7 +68,15 @@ numbers to get a pleasing result, or use it for your high school algebra
 class.
 
 
-### SPOILER:
+### NOTICE to those who wish for a greater challenge
+
+**If you want a greater challenge, don't read any further**:
+just try to understand the program via the source.
+
+If you get stuck, come back and read below for additional hints and information.
+
+
+### What this entry does:
 
 As should be obvious from 20 feet away, the program is a cubic plotter.
 It plots against certain artists, splattering their cubes with graphs
@@ -85,6 +93,9 @@ See the [gtface](%%REPO_URL%%/1994/horton/gtface.c) program for another example.
     ./gtface < gtface.data
 ```
 
+
+### How this entry works:
+
 For more information, see my article
 
 [Using GraphTab; USENIX ;login: Sept/Oct 1992, pages 28-31](login_sept92-pp28-31.pdf).

1994/horton/index.html

@@ -429,7 +429,11 @@ newsletter and a PDF file of just the pages cited.</p>
 <p>Run it with any 4 numeric arguments, e.g. <code>./horton 3 2 1 0</code>. Play with the
 numbers to get a pleasing result, or use it for your high school algebra
 class.</p>
-<h3 id="spoiler">SPOILER:</h3>
+<h3 id="notice-to-those-who-wish-for-a-greater-challenge">NOTICE to those who wish for a greater challenge</h3>
+<p><strong>If you want a greater challenge, don’t read any further</strong>:
+just try to understand the program via the source.</p>
+<p>If you get stuck, come back and read below for additional hints and information.</p>
+<h3 id="what-this-entry-does">What this entry does:</h3>
 <p>As should be obvious from 20 feet away, the program is a cubic plotter.
 It plots against certain artists, splattering their cubes with graphs
 of their cubic equations. Those dastardly arguments are mere coefficients,
@@ -439,6 +443,7 @@ It’s easily modified to graph <em>any</em> 96x160 bitmap on a dumb terminal.</
 <p>See the <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1994/horton/gtface.c">gtface</a> program for another example. Try:</p>
 <pre><code>    make gtface
     ./gtface &lt; gtface.data</code></pre>
+<h3 id="how-this-entry-works">How this entry works:</h3>
 <p>For more information, see my article</p>
 <p><a href="login_sept92-pp28-31.pdf">Using GraphTab; USENIX ;login: Sept/Oct 1992, pages 28-31</a>.</p>
 <pre><code>          MMMM,M,MM&quot;MM,,,

1994/imc/README.md

@@ -44,7 +44,16 @@ parameter or an invalid parameter is given, then 5 is assumed.  The
 maximum parameter is determined only by the amount of CPU time, virtual
 memory and display (or file) space available.
 
-### OBFUSCATION:
+
+### NOTICE to those who wish for a greater challenge
+
+**If you want a greater challenge, don't read any further**:
+just try to understand the program via the source.
+
+If you get stuck, come back and read below for additional hints and information.
+
+
+### How this entry works:
 
 OK, so you have probably seen magic square printers before.  But what
 about one that deals with even sizes as well as odd ones, or one that

1994/imc/index.html

@@ -424,7 +424,11 @@ other functions (apart from <code>main()</code>).</p>
 parameter or an invalid parameter is given, then 5 is assumed. The
 maximum parameter is determined only by the amount of CPU time, virtual
 memory and display (or file) space available.</p>
-<h3 id="obfuscation">OBFUSCATION:</h3>
+<h3 id="notice-to-those-who-wish-for-a-greater-challenge">NOTICE to those who wish for a greater challenge</h3>
+<p><strong>If you want a greater challenge, don’t read any further</strong>:
+just try to understand the program via the source.</p>
+<p>If you get stuck, come back and read below for additional hints and information.</p>
+<h3 id="how-this-entry-works">How this entry works:</h3>
 <p>OK, so you have probably seen magic square printers before. But what
 about one that deals with even sizes as well as odd ones, or one that
 prints out a different one each time (or attempts to, at any rate)?</p>

1994/schnitzi/README.md

@@ -83,6 +83,14 @@ You might also wish to redirect the output to another file,
 compile it and compare how it works to the original code.
 
 
+### NOTICE to those who wish for a greater challenge
+
+**If you want a greater challenge, don't read any further**:
+just try to understand the program via the source.
+
+If you get stuck, come back and read below for additional hints and information.
+
+
 ## Author's remarks:
 
 This is a program which takes any text file as input and 'flips'

1994/schnitzi/index.html

@@ -438,6 +438,10 @@ is different, but there is more than meets the <code>diff</code>’s eye. Can yo
 find out why?</p>
 <p>You might also wish to redirect the output to another file,
 compile it and compare how it works to the original code.</p>
+<h3 id="notice-to-those-who-wish-for-a-greater-challenge">NOTICE to those who wish for a greater challenge</h3>
+<p><strong>If you want a greater challenge, don’t read any further</strong>:
+just try to understand the program via the source.</p>
+<p>If you get stuck, come back and read below for additional hints and information.</p>
 <h2 id="authors-remarks">Author’s remarks:</h2>
 <p>This is a program which takes any text file as input and ‘flips’
 the input file along a diagonal running from the top left corner

1994/tvr/README.md

@@ -39,11 +39,19 @@ Mode may be a value from 0 to 12.
 
 ## Alternate code:
 
-The author provided us a spoiler version that might be of interest to some.
+
+### NOTICE to those who wish for a greater challenge
+
+**If you want a greater challenge, don't read any further**:
+just try to understand the program without looking at the Alternate code.
+
+If you get stuck, come back and look at the Alternate code.
 
 
 ### Alternate build:
 
+The author provided us a less obfuscated version that might be of interest to some.
+
 ``` <!---sh-->
     make alt
 ```

1994/tvr/index.html

@@ -416,8 +416,12 @@ code</a> below.</p>
 <pre><code>    ./try.color.sh              # for colour displays
     ./try.bw.sh                 # for Black &amp; White displays</code></pre>
 <h2 id="alternate-code">Alternate code:</h2>
-<p>The author provided us a spoiler version that might be of interest to some.</p>
+<h3 id="notice-to-those-who-wish-for-a-greater-challenge">NOTICE to those who wish for a greater challenge</h3>
+<p><strong>If you want a greater challenge, don’t read any further</strong>:
+just try to understand the program without looking at the Alternate code.</p>
+<p>If you get stuck, come back and look at the Alternate code.</p>
 <h3 id="alternate-build">Alternate build:</h3>
+<p>The author provided us a less obfuscated version that might be of interest to some.</p>
 <pre><code>    make alt</code></pre>
 <h3 id="alternate-use">Alternate use:</h3>
 <pre><code>    ./tvr.alt altmode screensize/2 &lt; colormapfile</code></pre>

1994/westley/README.md

@@ -111,7 +111,13 @@ To see the game from start to complete, try:
 
 Not all compiler errors are bad.
 
-For spoilers see the end of the notes from the author below.
+
+### NOTICE to those who wish for a greater challenge
+
+**If you want a greater challenge, don't read any further**:
+just try to understand the program via the source.
+
+If you get stuck, come back and read below for additional hints and information.
 
 
 ## Author's remarks:

1994/westley/index.html

@@ -463,7 +463,10 @@ arguments:</p>
 <pre><code>    ./try.sh</code></pre>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
 <p>Not all compiler errors are bad.</p>
-<p>For spoilers see the end of the notes from the author below.</p>
+<h3 id="notice-to-those-who-wish-for-a-greater-challenge">NOTICE to those who wish for a greater challenge</h3>
+<p><strong>If you want a greater challenge, don’t read any further</strong>:
+just try to understand the program via the source.</p>
+<p>If you get stuck, come back and read below for additional hints and information.</p>
 <h2 id="authors-remarks">Author’s remarks:</h2>
 <p>This program, in accordance with the rules, compiles into a legal
 C program without human intervention. However, it simply compiles