Suggestion regarding adding the "Reviewed On" link for github PR

[Gaurav Dhingra]

Hi everyone,

I was thinking that adding a "Reviewed On" github PR link to the commit would be good for future pull requests when the PR is being merged.
For example: i added on this "commit" https://github.com/sympy/sympy/commit/9e37659867322e7ba20b44984550cd5353e00931

```

Reviewed-on: #10505
```

Just to stress i am talking about adding it to "every commit".
Having such a link helped me looking for the related commits on github a little easy.
Does that sound like a good idea? ( i saw it on the source code of Libreoffice as well )

Gaurav Dhingra (gxyd)