Add repository attribute in Cargo.toml

[SOF3]

docs.rs shows the GitHub page iff package.repository is provided in Cargo.toml

Otherwise it just shows "Homepage", and doesn't display stars, issues, etc.

[casey]

Thank you for the PR!

Are you sure that the .git extension should be there? For example, in Cargo's Cargo.toml, the repository key is set to the GitHub URL without the .git extension.

[SOF3]

Perhaps not using the .git is better, I suppose. For GitHub though, both are equivalent, because cloning without .git will automatically redirect, and accessing repo webpage with .git will automatically redirect as well

[casey]

Sweet, merged!