am 5890600d: Add a better explanation about how to deal with user modules

Merge commit '5890600dac385941b6a4c6b6d0b230c1f13d54fa' into gingerbread-plus-aosp

* commit '5890600dac385941b6a4c6b6d0b230c1f13d54fa':
  Add a better explanation about how to deal with user modules