[llvm] [docs][bolt] Remove Markdown enum (PR #226411)

[Amilendra Kodithuwakku via llvm-commits]

amilendra wrote:

> LGTM. This should be a historical artifact and probably something we explicitly want to get rid of now that I believe all of the BOLT docs have been ported to markdown.

Thanks. I don't have merge access so please merge if you have permission.

https://github.com/llvm/llvm-project/pull/226411