fix the mistake of step orders

Refine the step order in training guide chapter 3

Closes-Bug: #1315239

Change-Id: Ib068b20b666177c50f772df85b849cea5b15665a
Clean up write-up about boot from volume

Partial-Bug: #1215515

Change-Id: I5eb42c3f7e071da2779c36a551bee0608316d093
author: diane fleming
Merge "Clean up write-up about boot from volume"
Merge "fix the mistake of step orders"