rustdoc_to_markdown: Add table support (#12488)

This PR extends `rustdoc_to_markdown` with support for tables:

<img width="1007" alt="Screenshot 2024-05-30 at 12 05 35 PM"
src="https://github.com/zed-industries/zed/assets/1486634/4e9a2a65-8aaa-4df1-98c4-4dd4e7874514">


Release Notes:

- N/A
c118012223Marshall Bowers committed on 5/30/2024, 4:17:10 PM· committed by GitHubparent7a30937
2 files changedLine totals unavailable