Notify that the submitter is also an author

[alitaheri]

Currently, the bot excludes the mention when the submitter of the PR is an author from the list.

This has a draw back. The other bot will mark the PR as unowned when there are no other authors.
And the members who take care of merging will have to manually check if the submitter is also an author.

I believe it's better if the bot comments:

The PR was submitted by an author.

...

[leonard-thieu]

I'm not sure this would solve the core issue. This seems like something that about be fixed in @typescript-bot itself.