[PATCH docs] Add doc for contribution guidelines

[Andrew Donnellan]

On 14/01/16 20:10, OpenBMC Patches wrote:
> +Use your full name for contributions, and include a "Signed-off-by" line,
> +to indicate that you agree to the Developers Certificate of Origin (see below).

"Developer's", for consistency :)

Otherwise looks excellent.

Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

-- 
Andrew Donnellan              Software Engineer, OzLabs
andrew.donnellan at au1.ibm.com  Australia Development Lab, Canberra
+61 2 6201 8874 (work)        IBM Australia Limited