Adjust documentation to mention Mercurial support

Signed-off-by: Michal Čihař <michal@cihar.com>
Setting version to 2.1
Document changes

Signed-off-by: Michal Čihař <michal@cihar.com>
Support native notifications on Mercurial repos from Bitbucket

Signed-off-by: Michal Čihař <michal@cihar.com>