README.md: multiple fixes

* Convert to markdown.
* Fix grammar.
* Fix link to generated documentation (supybot.fr.cr --> supybot.aperio.fr).
README.md: remove the second paragraph

> 2014-06-30 21:11:00+0300 < pinkieval> er

> 2014-06-30 21:11:09+0300 < pinkieval> you can remove the second
paragraph
Merge pull request #7 from Mkaysi/readme

README.md: multiple fixes
README.md: also mention readthedocs.org
README.md: use https:// for readthedocs.org
README.md: link to the documentation directly...

at supybot.aperio.fr
Merge pull request #9 from Mkaysi/readme

README.md: also mention readthedocs.org