Update the doc after llvm-svn: 364121 is landed.
With two more trivial fixes that are not related to
--disassemble-functions but still about llvm-objdump.
Reviewers: jhenderson, grimar, MaskRay, rupprecht, peter.smith
Reviewed by: jhenderson, MaskRay
Differential Revision: https://reviews.llvm.org/D63787
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364573 91177308-0d34-0410-b5e6-96231b3b80d8