Add glossary entries for Arch Design

Add new entries: north-south traffic, east-west traffic and TripleO.

Add entries for these terms to the Arch Design Guide. Use consistent
spelling for these entries.
Include some edits for improved wording.

Change-Id: Ic241664a44c0e41e3961206b626eef2acb0c5b31
Merge "Add glossary entries for Arch Design"