Slight change in 'greater challenge' line

In the line in README.md and index.html files that said:

    ### NOTICE to those who wish for a greater challenge

I added a ':' at the end of the line.

There were some entries that had a link fix in the index.html file but I
only looked up through 1995/leo as those still have to have a 'look and
feel' check and it would just slow things down.

2014/endoh1/README.md

@@ -62,7 +62,7 @@ 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
+### 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.

2014/endoh1/index.html

@@ -432,7 +432,7 @@ 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>
+<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>

2014/endoh1/quine-qr.md

@@ -1,4 +1,4 @@
-### NOTICE to those who wish for a greater challenge
+### 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.