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.

2004/anonymous/README.md

@@ -49,7 +49,7 @@ It was not until a sequel was called for that this was changed.
 
 If you want to read the first edition they reprinted it some years back: `The
 Hobbit Facsimile First Edition`. The details are also discussed in [History of
-Middle-earth (HoMe)](https://tolkiengateway.net/wiki/The_History_of_Middle-earth) VI, [The Return of the
+Middle-earth (HoMe)](https://tolkiengateway.net/wiki/The_History_of_Middle-earth) VI, [The Return of the
 Shadow](https://tolkiengateway.net/wiki/The_Return_of_the_Shadow), part one of
 the history of [The Lord of the
 Rings](https://en.wikipedia.org/wiki/The_Lord_of_the_Rings) of a twelve volume set - as well as in [The