Drive-by-fix: Clean up html header tags a bit

Change-Id: Ib9d3e0a24497f393b1d45b7b6ab46af381252613
No-Try: True
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3845076Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82620}