add contributing to distribution repo
add contributing to distribution repo

carlospontual/card.io-Android-source,carlospontual/card.io-Android-source,lkorth/card.io-Android-source,carlospontual/card.io-Android-source,lkorth/card.io-Android-source,lkorth/card.io-Android-source,carlospontual/card.io-Android-source,lkorth/card.io-Android-source,lkorth/card.io-Android-source,carlospontual/card.io-Android-source