settings: Improve example for RABBITMQ_HOST.
settings: Improve example for RABBITMQ_HOST.

We prefer 127.0.0.1 over localhost for RabbitMQ because of weird IPv6
issues, so we should avoid mentioning localhost as an example.

hackerkid/zulip,tommyip/zulip,tommyip/zulip,kou/zulip,synicalsyntax/zulip,punchagan/zulip,rishig/zulip,showell/zulip,rht/zulip,brainwane/zulip,kou/zulip,timabbott/zulip,eeshangarg/zulip,andersk/zulip,punchagan/zulip,timabbott/zulip,showell/zulip,hackerkid/zulip,hackerkid/zulip,eeshangarg/zulip,showell/zulip,shubhamdhama/zulip,tommyip/zulip,kou/zulip,showell/zulip,kou/zulip,zulip/zulip,tommyip/zulip,rishig/zulip,kou/zulip,andersk/zulip,shubhamdhama/zulip,zulip/zulip,rht/zulip,zulip/zulip,hackerkid/zulip,synicalsyntax/zulip,tommyip/zulip,punchagan/zulip,shubhamdhama/zulip,rht/zulip,synicalsyntax/zulip,timabbott/zulip,hackerkid/zulip,timabbott/zulip,zulip/zulip,brainwane/zulip,punchagan/zulip,synicalsyntax/zulip,showell/zulip,showell/zulip,eeshangarg/zulip,timabbott/zulip,tommyip/zulip,andersk/zulip,rishig/zulip,eeshangarg/zulip,shubhamdhama/zulip,punchagan/zulip,synicalsyntax/zulip,rishig/zulip,rht/zulip,rht/zulip,synicalsyntax/zulip,eeshangarg/zulip,rishig/zulip,rishig/zulip,andersk/zulip,andersk/zulip,showell/zulip,zulip/zulip,shubhamdhama/zulip,punchagan/zulip,andersk/zulip,eeshangarg/zulip,kou/zulip,eeshangarg/zulip,zulip/zulip,brainwane/zulip,hackerkid/zulip,andersk/zulip,rht/zulip,brainwane/zulip,tommyip/zulip,rishig/zulip,zulip/zulip,brainwane/zulip,hackerkid/zulip,timabbott/zulip,punchagan/zulip,synicalsyntax/zulip,timabbott/zulip,shubhamdhama/zulip,brainwane/zulip,shubhamdhama/zulip,rht/zulip,kou/zulip,brainwane/zulip