updating README to tell developers to use 0.6.3 in config.gem
updating README to tell developers to use 0.6.3 in config.gem

rubyist/clearance,benlivermore/clearance,pedrosmmoreira/clearance,rubyist/clearance,benlivermore/clearance,thoughtbot/clearance,pedrosmmoreira/clearance,janusnic/clearance,sferik/clearance,zernie/clearance,naveed-ahmad/clearance,thoughtbot/clearance,zernie/clearance,naveed-ahmad/clearance,crowdtap/clearance,janusnic/clearance,janusnic/clearance,pedrosmmoreira/clearance,naveed-ahmad/clearance,zernie/clearance,crowdtap/clearance,benlivermore/clearance,crowdtap/clearance,openeducation/clearance,thoughtbot/clearance