doc: Initial platform configuration guides

Adds infrastructure for platform configuration guides,
starting with the fsl_frdm_k64f platform configuration.

Incorporates inline sphynx tags except :guilabel:
which does not bold gui labels, a feature needed
for scanning a procedure for key info.

Change-Id: I4f5154dae896449fb709842501c69d8757deca3e
Signed-off-by: Carol Lee <carol.lee@windriver.com>
3 files changed