[llvm] [Docs] Fix large vertical space at top of pages (PR #81599)

[J. Ryan Stinnett via llvm-commits]

jryans wrote:

I wasn't too sure who to select for reviewers here, as I don't think many work on docs styling... 😅 If you have any reviewer suggestions, please add them!

https://github.com/llvm/llvm-project/pull/81599