C2MS12 — in 8.1, we sometimes have table and section names that have wrong term

In this section, anytime we have a table or subsection or diagram name it should always be C2MS Message Envelope, instead of simply Message Envelope. The type is the former.

Use complete name for C2MS Message Envelope in Headers and Titles

In Section 8.1, ensure "C2MS Message Envelope" is used instead of "Message Envelope" in section and table titles. Also do this when referring to the class name. When not referring to the full class name, soften Message Envelope to message envelope.