Append latest commit link to package update notification

[Lukas Fleischer]

On Thu, 30 Apr 2020 at 15:26:08, Daniel M. Capella wrote:
> > So appending latest commit link "helps" and "encourages" people to
> > check latest update and I don't think in any possible way has a
> > downside except for a little more text to email which I assume it's
> > OK.
> [...]
> IIRC when I had suggested this feature previously, it had gotten a
> thumbs up, just requires someone take the time to write the code.

Agreed. Note that adding a single commit may not be enough since
multiple commits can be pushed at once. We should either include links
to all new commits or add a link to a diff comprising all commits.