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.

2011/richards/README.md

@@ -31,7 +31,7 @@ For more detailed information see [2011/richards in bugs.html](../../bugs.html#2
 ## Judges' remarks:
 
 Oh no, yet another
-[dc](https://en.wikipedia.org/wiki/Dc_(computer_program))-style calculator? (see
+[dc](https://en.wikipedia.org/wiki/Dc_(computer_program))-style calculator? (see
 [2000/dlowe](../../2000/dlowe/index.html) using an embedded Perl interpreter and deemed `Worst
 Abuse of the Rules`).  Well, this one does it (expression calculation, that is,
 not the rule abuse) in a different way.  The author claims that his calculator
@@ -42,7 +42,7 @@ without attempting to unravel the source?
 ## Author's remarks:
 
 This is an implementation of the classic UNIX
-[dc](https://en.wikipedia.org/wiki/Dc_(computer_program)) command, the
+[dc](https://en.wikipedia.org/wiki/Dc_(computer_program)) command, the
 [reverse Polish](https://en.wikipedia.org/wiki/Reverse_Polish_notation)
 calculator. Actually it's a pretty bad implementation, since it only implements
 32-bit integers (well, `sizeof(int)`-sized integers). It only implements the