Feature request: document why a shape handle might get deleted

Is your feature request related to a problem? Please describe. People wonder why shapes get deleted. Especially if they have very large shapes as recreating and reloading them into clients can get expensive.

If they understand why it's happening, they might be able to reduce how often shapes are recreated by e.g. preserving their shapes logs when restarting their Electric instance.

Describe the solution you'd like Document the reasons for shape deletions:

1. the server is restarted and loses all its shape logs
2. pg has an error of some sort that isn't recoverable so electric deletes all the shapes
3. probably most common, there's a schema change to the table the shape uses so the log is missing the new data