Added information about the variable consul_join_at_start to the README file.
Added information about the variable consul_join_at_start to the README file.

jivesoftware/ansible-consul,jonbrandenburg/ansible-consul,robbiet480/ansible-consul,jivesoftware/ansible-consul,wernerb/ansible-consul-yum,lbaldwin123/ansible-consul,trumant/ansible-consul,adriagalin/ansible-consul,jonbrandenburg/ansible-consul,savagegus/ansible-consul,adriagalin/ansible-consul,lbaldwin123/ansible-consul,wernerb/ansible-consul-yum,trumant/ansible-consul,robbiet480/ansible-consul,savagegus/ansible-consul,MrMMorris/ansible-consul,msabramo/ansible-consul,tomjrob/ansible-consul,cloudstrap/ansible-consul,tomjrob/ansible-consul,MrMMorris/ansible-consul,cloudstrap/ansible-consul,msabramo/ansible-consul