Page should not link to itself.

Reading for content; editing for consistency.

This way MkDocs will be able to report errors for broken links

Done with:

perl -0777 -i -pe \
's@(?<!!)\[([^\]]*)\]\((?!https?://)(?!mailto:)(/(?:(?:(?:/(?![\)#]))|[^/)#])(?!.md))+)/?(#[^)]*)?\)@[$1]($2.md$3)@gm' \
`find . -name '*.md'`

Close #86

1) This seems like a site admin task, not a developer task. If you're reading this page, I assume you
   already know how to do this. I'd argue this belongs in the user guide (if it's not already there).
2) It doesn't seem right to me that one should configure their extensions directory before
   deciding whether or not to write an extension. First check the extensions directory to
   see if someone has already built the thing. If not, only then does make sense to start
   playing with your environment config.
3) If we keep it in the developer guide, I'd put it at the beginning of the instructions
   for creating a module extension (https://wiki.civicrm.org/confluence/display/CRMDOC/Create+a+Module+Extension).
   These are currently undergoing migration from the wiki to mkdocs, so I'm blocked from making such
   an update at this time.

Original here:
https://wiki.civicrm.org/confluence/display/CRMDOC/Create+a+Module+Extension

still missing some macro content! :-/

This completes transfer of

https://wiki.civicrm.org/confluence/display/CRMDOC/Create+an+Extension

This page is yet to do:

https://wiki.civicrm.org/confluence/display/CRMDOC/Create+a+Module+Extension