[docs][llvm-objcopy][llvm-strip] Improve --strip-unneeded description

Behaviour was recently added to this switch to strip debug sections too.
See r369761.

This change also makes the description for the --strip-unneeded switch
consistent between the two docs.

Reviewed by: MaskRay

Differential Revision: https://reviews.llvm.org/D67546

llvm-svn: 371855
diff --git a/llvm/docs/CommandGuide/llvm-objcopy.rst b/llvm/docs/CommandGuide/llvm-objcopy.rst
index 065811c..0472117 100644
--- a/llvm/docs/CommandGuide/llvm-objcopy.rst
+++ b/llvm/docs/CommandGuide/llvm-objcopy.rst
@@ -123,7 +123,7 @@
 .. option:: --strip-unneeded
 
  Remove from the output all local or undefined symbols that are not required by
- relocations.
+ relocations. Also remove all debug sections.
 
 .. option:: --version, -V
 
diff --git a/llvm/docs/CommandGuide/llvm-strip.rst b/llvm/docs/CommandGuide/llvm-strip.rst
index fb1d5a1..a4f497a 100644
--- a/llvm/docs/CommandGuide/llvm-strip.rst
+++ b/llvm/docs/CommandGuide/llvm-strip.rst
@@ -97,7 +97,8 @@
 
 .. option:: --strip-unneeded
 
- Remove all local or undefined symbols that are not required by relocations.
+ Remove from the output all local or undefined symbols that are not required by
+ relocations. Also remove all debug sections.
 
 .. option:: --version, -V