Add Formatters README section

Explains and gives an example of each of the currently available
formatters.

Change-Id: I8a3a9f1e8fdaf50085773ef5e5a64d6628d53f38
Reviewed-on: https://gerrit.causes.com/33683
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>