Add docs for corobo setup with gitter

The corobo setup process is a bit tedious and involves a number of configurations(setting environment variables, etc.). There should be some detailed documentation about the corobo setup process in text mode as well as with gitter backend.

Start by reviewing the corobo setup process and its configuration requirements, including environment variables. Document setup in text mode and with the gitter backend, covering the required configuration so a newcomer can complete either setup path.

Written by the indexing model from the issue text.