Install Guide: Fix Typos In Neutron Compute Node

Similarly to the previous commit, this commit fixes a series of
typos in the compute node section.

This is the third commit in the series

backport: havana

Change-Id: I60916f86788dbc6e2837a4e6245be7aaf83099cd
Install Guide: Fix Typos in Neutron Controller

Similiarly to the previous two bugs, this commit fixes
general typos in the controller node section of the Neutron
documentation.

This is the fourth commit in the series

Change-Id: I90616f3ca493ba86c76ca7976d2e70cbb9a6905d
Fixes: bug #1243237
Merge "Install Guide: Fix Typos In Neutron Compute Node"
Merge "Install Guide: Fix Typos in Neutron Controller"