[doc] added depends cross compile info
[doc] added depends cross compile info

Conflicts:
	doc/build-unix.md

Github-Pull: #7747
Rebased-From: 3e55b3a00450279522900ca96e5cf79162169019

faircoin/faircoin2,faircoin/faircoin2,jaromil/faircoin2,jaromil/faircoin2,faircoin/faircoin,faircoin/faircoin2,jaromil/faircoin2,faircoin/faircoin,jaromil/faircoin2,faircoin/faircoin,faircoin/faircoin2,faircoin/faircoin,faircoin/faircoin,faircoin/faircoin2,faircoin/faircoin2,jaromil/faircoin2,jaromil/faircoin2,faircoin/faircoin