docs: Add Guide to Hosting a Coffee Table Group

[meg-gutshall]

Summary

Context

I think we need some general documentation around what is expected of a Coffee Table Group Host and how this role has separate responsibilities from Coffee Table Group Lead (though one can have both roles).

Goals

I would like to evaluate the content we already have to see if it is still applicable. Then, I'd like to use the relevant information along with some observations I've made through trial and error to achieve the following:

• Craft a complete description of the Coffee Table Groups Host role
• Identify a comprehensive list of the Coffee Table Groups Host's duties
• Determine if another Coffee Table Groups volunteer role is needed to support the Coffee Table Groups Host role
  • Yes, Coffee Table Groups Lead role

Collaborators

@abbeyperini and @tkshill – If either of you have any feedback, feel free to contribute!