Fixes in 1998 html files

This includes some notices to those who wish for a greater challenge.

In the 1998/schweikh3 the man page (and its copy to demonstrate the
entry) have been updated slightly but only in comment (move 'or' from
the command suggested to render it in text to its own line before the
next command also in comment).

The bugs file was updated for an entry or two.

1998/schweikh2/README.md

@@ -137,6 +137,14 @@ and now it works with both clang and gcc.
 
 ## Author's remarks:
 
+### 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 program does
 
 My entry is a `yarng`, which stands for, you guessed it, yet another
@@ -167,7 +175,7 @@ For example:
 
 ### Why I think this is obfuscated
 
-- Ever seen a 'do for ... while' loop?
+- Ever seen a `do for ... while` loop?
 
 - I avoided `int` like the plague. Instead I used storage class specifiers
 (`register`, `auto`) to get implicit `int`. The Standard allows implicit `int` even in