OSHMEM: add missing help file, got lost during merge. Thanks to Yossi/Igor for finding it.

Change-Id: I466e40a3fea70e8045dd1e897edcc50ccf0451a3

Conflicts:
	oshmem/mca/sshmem/base/Makefile.am
	oshmem/mca/sshmem/base/help-oshmem-sshmem.txt