Update README
Update README

Make it clearer what dependencies are needed for
builiding and add download link.

Hajto/erlangpl,erlanglab/erlangpl,erlanglab/erlangpl,Baransu/erlangpl,Hajto/erlangpl,Hajto/erlangpl,mkacper/erlangpl,Baransu/erlangpl,mkacper/erlangpl,mkacper/erlangpl,Baransu/erlangpl,erlanglab/erlangpl