[docs][llvm-dwarfdump] Fix the warnings during docs-llvm-html buil

Before the fix the build of docs-llvm-html would fail.
The D80959 introduced options that are not recognized, so we have
warning as:

  llvm-project/llvm/docs/CommandGuide/llvm-dwarfdump.rst:40\
  :unknown option: --debug-info

Differential Revision: https://reviews.llvm.org/D82460