[llvm] [NFC] Add missing bitcode documentation to BitCodeFormat.rst (PR #102555)

[Chris Apple via llvm-commits]

cjappl wrote:

Yeah. This seems ripe for a problem.

Let me close this review and I'll put up a review just deleting the list, better to do it right while it's on my mind than do half measures.

I'll ping you two on that review shortly.

https://github.com/llvm/llvm-project/pull/102555