Add documentation about meetings

[SaschaSchwarze0]

We should add documentation about our meetings:

• Community meeting
• Refinement

The documentation should include information about how one contributes (like adding topics to the issue for the community meeting). It should explain what we are doing there, this is especially necessary for the refinement which is less "free" but more "formal". And it should explain the role and responsibilities of the moderator (like getting an overview before the refinement).

In addition, we want to use it to have a plan on who moderates when.

[coreydaley]

@SaschaSchwarze0 Do you have any thoughts on where we should host this information? Should it be in the shipwright-io/community/README.md? Or the shipwright-io/.github/CONTRIBUTING.md?

[SaschaSchwarze0]

I personally prefer the primary location to be README and then it can be linked to from other places such as CONTRIBUTING.