Fix numbering in devtest doc

The "source cloudprompt" step is messing up the numbering of the
online documentation.  I believe that's because of the lack of
indentation on the command (which I assume should remain commented
out since it's only supposed to be run once), so this just adds
indentation.

Change-Id: Ib926a001ee2fbca4e7dae2d5563121795a5cfdaa
Merge "Fix numbering in devtest doc"