Move the installation and configuration docs up a level.
Review Request #10066 — Created July 3, 2018 and submitted
When deployed on the website, most of the RB Gateway documentation was
nested in a
rbgateway/<version>/rb-gateway/, which wasn't really
necessary for namespacing. This change fixes that by moving the docs up
a level in the tree.
Built the docs. Tested that the links worked, there were no errors, and
the URLs were what I expected.