Fix grammatical errors in instance management case study

There are a few grammatical errors in the instance management case
study.  This commit fixes them.

Co-Authored-By: Shellee Arnold <shellee.arnold@hp.com>

Change-Id: Ia0b62a4de4721226e6b49305f6f71cbfee26e1ae
Closes-Bug: #1343549
Merge "Fix grammatical errors in instance management case study"