Few QoL changes for using react-grab for longer review sessions, UAT like things

Hello 👋

Been really enjoying react-grab, and using it for a purpose it was perhaps not designed for. Longer review sessions of user journeys through the apps, somewhat like a UAT session.

In doing so, there are two limitations that have been making it a bit less useful:

- When saving comments, its limited to 20 comments. If you comment more than 20, the oldest gets silently dropped. It would be nice to either tell the user it would happen, or ideally just not limit the count on these.
- The comments do not contain the URL in the selector stuffs, which can make it hard to identify what page the comment is related to on multi-page reviews