Clarified example 'my.cnf' under MySQL configuration

Removed invalid lines from example 'my.cnf' and added [mysqld]
section header to clarify location of 'bind-address' directive.
Patch applies to all distributions.

Change-Id: Ieacac9df8162e2d44f7576b858131ec3e7e6f43a
Closes-Bug: #1258276
(cherry picked from commit 0bba9cc21faf4140d51c9ca073068b073dbf51da)
Merge "Clarified example 'my.cnf' under MySQL configuration" into stable/havana