docs: add document for the compatibility library Change-Id: I1825ae1fba0be664a7c6a8b0ba32166f216a893f
most importantly, information about using <compatible-screens> also add sample code to <compatible-screens> doc Change-Id: I62f6ceee4e358a18f5e513cf54c9c96f27470ae9
Change-Id: I8d0eefd97e25cda691b1035129a50e1b902ab6e7