Update SortedProperties documentation

Elaborate on the behavior of the `SortedProperties` linter when the
`order` option is specified.

Change-Id: I8b50f272e3733c3a363fa794f544259911db326b
Reviewed-on: http://gerrit.causes.com/36071
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>