[clang-tools-extra] [clangd] Improve Markup Rendering (PR #140498)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

Carrying over review request to @kadircet from the original combined patch at https://github.com/llvm/llvm-project/pull/128591#issuecomment-2782334206:

> @kadircet, you were involved with earlier rounds of review on the old patch (https://reviews.llvm.org/D143112) and design discussions in the issue (https://github.com/clangd/clangd/issues/529) -- do you by chance have the cycles to pick up this review?

https://github.com/llvm/llvm-project/pull/140498