Documentation: Combine M component preparation docs

Take the duplicate code regarding the preparation of the M components for
import found in the two Import files and combine them into
one .rst file called PrepareMComponents.

Add that file to the README.

OSEHRA-Id: http://issues.osehra.org/browse/OAT-65
Change-Id: I0a89db4536e8f78811fecd31d99cdeb3f7b6eafc