With https://github.com/rust-lang/mdBook/pull/1641 merged, we can now test out the right-to-left rendering. We should 1. Update `mdbook` to use a version from Git (edit `.github/workflows/install-mdbook/action.yml`). 2. Enable publication for #671. 3. Ensure that Persian is rendered nicely (ask @mbpouri and @DannyRavi for input).