Changelog commit links broken in release branches

[ilikepi]

Just a heads up that the commit links in CHANGELOG.md are broken in the release branches. This is because they are relative links starting with "../..". The release branch naming convention includes a / which winds up in the path of the URL when viewing CHANGELOG.md on github.com, so the relative links would need one additional "../" to resolve correctly in Github's URL scheme. I'm happy to submit a PR for this against the release branches, but I wasn't sure if the change would be overwritten by a script the next time a release was created...

Also note that if you test this yourself, the commit link at the top of CHANGELOG.md in master uses an invalid commit hash. Presumably the original commit was rewritten during the PR that added it.