Added complete Doc Convention to config-reference guide.

backport: havana

Change-Id: I0936caed5cac45373df9bbc077f66bcfa2f96b58
Partial-Bug: #1121866
(cherry picked from commit 7ac18a94b82bdf9b09a4c90d01664ac29e2ad13b)
Fix ambiguity and duplication in network install

As noted in the bug report, the initial paragraph confused where the
commands were to be run.

Additionally, database configuration is done in the 'configuring a
compute node' section, and was duplicated here.

Change-Id: If162d588f1d2c3eb85600c1cc481def9377ce94e
Backport: havana
Closes-Bug: 1256188
(cherry picked from commit ade99ab04ee6f844816458f044a013a657e6da3d)
Merge "Fix ambiguity and duplication in network install" into stable/havana
Merge "Added complete Doc Convention to config-reference guide." into stable/havana