Feature request: The error message from Dolt when failing a write because the database is read-only should be better.

As per #10852, if you run a Dolt CLI command against a locked database, it will fail with a pretty obscure message: `cannot update manifest: database is read only`. This should be better.

The suggestion in the linked issue is to add:

`database is read only (another process holds .dolt/noms/LOCK — check lslocks)`

I think that makes sense on Linux, but guiding towards `lslocks` on other platforms is probably wrong. Regardless, a message indicating that another Dolt process is (or was) running concurrently and the user should go looking for it is probably appropriate.

Start with the failure described in #10852 by running a Dolt CLI command against a locked database and tracing the source of `cannot update manifest: database is read only`. Decide on platform-neutral wording that indicates another Dolt process may hold or have held the lock; done means the failure message gives that guidance without directing users on all platforms to `lslocks`.

Written by the indexing model from the issue text.