am b9cb731b: am b7cfc618: am 28fb09e0: cherry pick Change-Id: I183ff47e59617b2c17a92b876ca8c8bcc9b45262 docs: add document for the compatibility library

* commit 'b9cb731bb89bd310a17093262ce6483c557d3d4c':
  cherry pick Change-Id: I183ff47e59617b2c17a92b876ca8c8bcc9b45262 docs: add document for the compatibility library