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.

2014/endoh1/README.md

@@ -62,6 +62,14 @@ more than 1000 words.
 You may want to use a large display with a very small terminal font.
 
 
+### 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.
+
+
 ### Q(uine)R code generator
 
 See [quine-qr.html](quine-qr.html).

2014/endoh1/index.html

@@ -432,6 +432,10 @@ more than 1000 words.</p>
 <h2 id="authors-remarks">Author’s remarks:</h2>
 <h3 id="remarks">Remarks</h3>
 <p>You may want to use a large display with a very small terminal font.</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="quiner-code-generator">Q(uine)R code generator</h3>
 <p>See <a href="quine-qr.html">quine-qr.html</a>.</p>
 <!--

2014/endoh1/quine-qr.html

@@ -383,6 +383,10 @@
 <!-- START: this line starts content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
 
 <!-- BEFORE: 1st line of markdown file: 2014/endoh1/quine-qr.md -->
+<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>
 <h1 id="quiner-code-generator">Q(uine)R code generator</h1>
 <h2 id="what-is-difficult">What is difficult?</h2>
 <p>As you may know, QR code (specification: ISO/IEC 18004) is quite complex. It

2014/endoh1/quine-qr.md

@@ -1,3 +1,11 @@
+### 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.
+
+
 # Q(uine)R code generator
 
 ## What is difficult?