Cleanups for Install Guide

The purpose of this patch is to host minor cleanups for the
recently added install guide content.

Feedback to address includes:

* Ensuring ubuntu;debian is used in the most appropriate way
* determining the appropriate prompt (# vs $ vs sudo) is used

So far this patch does not address these, but it was necessary
to move the conversation away from an already merged patch :)

Change-Id: Iaac4db7f99149a149dd6af0da4a9b18fa278cc3e
Merge "Cleanups for Install Guide"