Update docs around vim's substitute command (#29404)

With the introduction of
https://github.com/zed-industries/zed/pull/28138, the current vim docs
became stale.

This PR makes a small update to the docs to reflect this.
53b36b328ealexfertel committed on 4/28/2025, 4:53:01 PM· committed by GitHubparentce93961
1 file changedLine totals unavailable