[docs][llvm-nm] Add missing options to documentation
[docs][llvm-nm] Add missing options to documentation

There were several options missing from the documentation. This patch
adds them as well as improving some wording and separating the Mach-O
only options into a separate section.

Fixes https://bugs.llvm.org/show_bug.cgi?id=42234.

Reviewed by: MaskRay

Differential Revision: https://reviews.llvm.org/D63655

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@364176 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm