Send a notification when a pull request comment is edited

When somebody comment on your pull request you get a notification which is optionally also being forwarded as an e-mail. This is nice as you don't need to visit the PR to get to know the comments (and you can even reply via e-mail).

However if the comment is modified you won't get a new notification - and this can cause problems, like when somebody commenting "Good job!", but then editing to "Good job, but make sure to do x, y, z.". You probably won't visit the PR as you already got notified about the comment and it doesn't require any action from you, thus you won't see the edited version.

My suggestion would be to also send notifications on comment edits (and probably to send the first notification about 30s after the comment was made, so it can include any quick edits too).

This is true for pull request comments but probably also for commit diff line comments - the same issue.