Verbose update README.markdown
Verbose update README.markdown

Added detailed installation notes for Ubuntu, Debian and Tails
iseeareddoor/xmpp-client,agl/xmpp-client,thommfullery/birdcannon,isislovecruft/xmpp-client,twstrike/xmpp-client,isislovecruft/xocolatl,Yawning/ricochet-client,paulperegud/xmpp-client