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.

1998/schnitzi/README.md

@@ -116,6 +116,14 @@ looping.  To see the resulting program run, redirect the output from
 and then compile it.
 
 
+### 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.
+
+
 ### Obfuscation hints:
 
 The big key to this program is figuring out what the names of the

1998/schnitzi/index.html

@@ -470,6 +470,10 @@ looping. To see the resulting program run, redirect the output from
 <code>schnitzi</code> into another file, like this</p>
 <pre><code>    ./schnitzi 4 &gt; sort.c</code></pre>
 <p>and then compile it.</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>
 <h3 id="obfuscation-hints">Obfuscation hints:</h3>
 <p>The big key to this program is figuring out what the names of the
 functions ought to be; a bit of research may allow you to guess at