Add a CommandGuide for llvm-objdump

Summary:
Add a CommandGuide for llvm-objdump summarizing its usage along with some
general context.

Reviewers: beanz

Reviewed By: beanz

Subscribers: Eugene.Zelenko, llvm-commits

Differential Revision: https://reviews.llvm.org/D50034

llvm-svn: 339250
diff --git a/llvm/docs/CommandGuide/index.rst b/llvm/docs/CommandGuide/index.rst
index 95efffd..fca5a42 100644
--- a/llvm/docs/CommandGuide/index.rst
+++ b/llvm/docs/CommandGuide/index.rst
@@ -23,6 +23,7 @@
    llvm-ar
    llvm-lib
    llvm-nm
+   llvm-objdump
    llvm-config
    llvm-diff
    llvm-cov