Improve markdown guidelines wording

Amongst the changes here is that we do not need to have the hex or html
code (numbers) for open and close parentheses (in links) as there are
names. '(' is & followed by lpar; and the ')' is the same but 'rpar;'
instead. This makes it easier to remember and type and it generates the
same html as well (they are all valid). Now the markdown files are
consistent in this (in some cases hex was used and in others the html
code).

Although many markdown files were updated no html files needed to be
updated as it generates the same html. Even so I ran the appropriate
rules to do so just to verify this.

thanks-for-help.md

@@ -2409,7 +2409,7 @@ Cody also added the [try.sh](%%REPO_URL%%/1994/ldb/try.sh) script.
 </div>
 
 [Cody](#cody) added two alt versions, [one which uses
-fgets_&#x28;&#x29;](%%REPO_URL%%/1994/schnitzi/schnitzi.alt.c) but when fed its own source code cannot
+fgets_&lpar;&rpar;](%%REPO_URL%%/1994/schnitzi/schnitzi.alt.c) but when fed its own source code cannot
 generate code that compile and another [one with a bigger buffer
 size](%%REPO_URL%%/1994/schnitzi/schnitzi.alt2.c) which, when fed its own source code, will
 generate compilable code but not with the same buffer size but rather the