Improve install documentation for configuring database

* add note about having to modify the instructions if following
  non-standard procedure (e.g. servermon on its own db, etc)
* fix bad formatting which was running lines together (without a
  blankline after the XXXX:: line)
* reword one grammatically confusing sentence (tautology)
Merge pull request #67 from rowanthorpe/improve-docs-install-configuring-database

Improve install documentation for configuring database