Zulip automation for external Jupyter communities (Reddit etc)

Supporting Jupyter users is an important goal of the Docs Working Group. There has been some [discussion on the Jupyter Zulip](https://jupyter.zulipchat.com/#narrow/channel/103349-ask-anything/topic/support.20outside.20zulip/near/485586320) to add automations for Reddit or other external sites, so that Jupyter contributors can better support the community. We should investigate!