Add README.md to module package with instructions how to create a module
Add README.md to module package with instructions how to create a module

Summary: Adding instructions about Buck modules.

Reviewed By: sbalabanov

fbshipit-source-id: eb0c024

JoelMarcey/buck,brettwooldridge/buck,nguyentruongtho/buck,kageiit/buck,rmaz/buck,SeleniumHQ/buck,JoelMarcey/buck,shs96c/buck,SeleniumHQ/buck,shs96c/buck,kageiit/buck,romanoid/buck,facebook/buck,nguyentruongtho/buck,shs96c/buck,JoelMarcey/buck,shs96c/buck,romanoid/buck,facebook/buck,Addepar/buck,SeleniumHQ/buck,facebook/buck,SeleniumHQ/buck,SeleniumHQ/buck,nguyentruongtho/buck,kageiit/buck,JoelMarcey/buck,romanoid/buck,SeleniumHQ/buck,rmaz/buck,brettwooldridge/buck,zpao/buck,Addepar/buck,SeleniumHQ/buck,kageiit/buck,Addepar/buck,nguyentruongtho/buck,romanoid/buck,kageiit/buck,JoelMarcey/buck,romanoid/buck,SeleniumHQ/buck,brettwooldridge/buck,brettwooldridge/buck,SeleniumHQ/buck,rmaz/buck,Addepar/buck,Addepar/buck,JoelMarcey/buck,zpao/buck,brettwooldridge/buck,brettwooldridge/buck,facebook/buck,rmaz/buck,brettwooldridge/buck,brettwooldridge/buck,rmaz/buck,shs96c/buck,Addepar/buck,zpao/buck,SeleniumHQ/buck,rmaz/buck,brettwooldridge/buck,shs96c/buck,brettwooldridge/buck,romanoid/buck,shs96c/buck,rmaz/buck,Addepar/buck,shs96c/buck,rmaz/buck,JoelMarcey/buck,romanoid/buck,zpao/buck,JoelMarcey/buck,romanoid/buck,nguyentruongtho/buck,romanoid/buck,facebook/buck,facebook/buck,rmaz/buck,Addepar/buck,kageiit/buck,SeleniumHQ/buck,shs96c/buck,SeleniumHQ/buck,zpao/buck,nguyentruongtho/buck,Addepar/buck,zpao/buck,JoelMarcey/buck,Addepar/buck,shs96c/buck,rmaz/buck,shs96c/buck,JoelMarcey/buck,romanoid/buck,romanoid/buck,nguyentruongtho/buck,brettwooldridge/buck,facebook/buck,rmaz/buck,zpao/buck,shs96c/buck,Addepar/buck,shs96c/buck,kageiit/buck,SeleniumHQ/buck,romanoid/buck,Addepar/buck,Addepar/buck,rmaz/buck,JoelMarcey/buck,brettwooldridge/buck,brettwooldridge/buck,romanoid/buck,rmaz/buck,JoelMarcey/buck,JoelMarcey/buck