Added github repo to metadata and made Changes file conform to CPAN::Changes::Spec

Hi,

I added [GithubMeta] to dist.ini so the github repo will appear in the dist's metadata. This means it will be displayed in the sidebar on MetaCPAN, for example.

I also tweaked the formatting of Changes to conform to CPAN::Changes::Spec. This helps various tools process your dist, including MetaCPAN.

Cheers,
Neil