[boost] [git] Editing the release notes with github.

Hi, Obviously there won't be a release for a little while, but if you want to add anything you can now add changes to the release notes through the github web interface. Go to the quickbook source at: https://github.com/boostorg/website/blob/master/feed/history/boost_1_56_0.qb... And click 'edit' and make your changes. This will create a pull request. Hopefully this will make life a little easier. Although nothing will appear on the site at the moment because the web server is still based on subversion, but I should move it to git soon. Daniel