[llvm-objcopy][MachO] Implement --remove-section

Reviewers: alexshap, rupprecht, jhenderson

Reviewed By: rupprecht, jhenderson

Subscribers: jakehehrlich, abrachet, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66282
diff --git a/llvm/docs/CommandGuide/llvm-objcopy.rst b/llvm/docs/CommandGuide/llvm-objcopy.rst
index 9d7cab9..689ebb7 100644
--- a/llvm/docs/CommandGuide/llvm-objcopy.rst
+++ b/llvm/docs/CommandGuide/llvm-objcopy.rst
@@ -107,6 +107,9 @@
  Remove the specified section from the output. Can be specified multiple times
  to remove multiple sections simultaneously.
 
+ For MachO objects, ``<section>`` must be formatted as
+ ``<segment name>,<section name>``.
+
 .. option:: --set-section-alignment <section>=<align>
 
  Set the alignment of section ``<section>`` to `<align>``. Can be specified