doc: add links and backticks around names

* add backticks around names
* add single quotes around event names
* add parenthesis after function names
* add internal links between different sections
* add external links to MDN for some JavaScript references
* sort the link definitions alphabetically

PR-URL: https://github.com/nodejs/node/pull/4054


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>