Minor "adb help" fixes.

One day we should slim this down. (Maybe implement the "help" versus
"help all" distinction that doesn't currently exist but was documented
before this change.)

Bug: https://code.google.com/p/android/issues/detail?id=158394
Change-Id: Ie24b588ffea00d262ce7ab0e5c328120ba8af240
1 file changed