Edit Intro section of Cloud Admin Guide Compute chapter

Remove deprecated information
Correct figures
Edit grammar and style
Introduce refs to other guides
Change Nova to Compute

Change-Id: Icbf1a38e2d233ac3255858246b471a0c849c405b
Partial-bug: #1222003
Author: Nermina Miller
Merge "Edit Intro section of Cloud Admin Guide Compute chapter"