Add detailed documentation guidelines.

The guidelines include information regarding: lists, modular writing,
notices, parallelism and simple English.

Also includes the capitalization, punctuation and spelling conventions
for the project.

Change-Id: I754f492db41dc5cc2432d03441b0526603b043e6
Signed-off-by: Rodrigo Caballero <rodrigo.caballero.abraham@intel.com>