Docs: Various markdown fixes
Three commits that fix and clean up MarkDown files in doc/
, by:
- Using correct reference-link syntax, in two files
- Harmonizing heading style in
Understanding-SpiderMonkey-code.md
with rest of docs - Removing trailing hashes from
## This style of heading ##
, only used on some headings in four docs.
(The second and third commits aren't strictly necessary, as the code they replace is perfectly valid MarkDown. However, they stuck out as unnecessarily different from the style used in all the rest of the docs.)