Proposal process proposal

As discussed in the Haskell Foundation Slack, we need a proposal process that balances open participation with the ability for people to work out details quickly.

This process specifies only what happens once the proposers are ready for review, and selects the hf/proposals gitlab repo as the location of record for all proposals, underway or completed.

proposals.md

@@ -8,6 +8,8 @@ This process is open to anyone in the community with ideas on how the Haskell Fo
 
 Proposals are created as Merge Requests in the [proposals](https://gitlab.haskell.org/hf/proposals) repository of the [Haskell GitLab](https://gitlab.haskell.org/). Create a markdown file with an appropriate name, define the proposal as described below, and open an MR when you are ready for comments and review.
 
+If a contributor has an idea for change, but that idea is not yet fully-formed into a proposal, they should open a new Issue (not a Merge Request) in the [proposals](https://gitlab.haskell.org/hf/proposals) repo. The community can then work to refine that idea into a proposal, eventually making an MR with a more fleshed-out idea. Issues will not be submitted to the Board for approval, as the approval process requires the details that comprise a proper proposal.
+
 ## Community Notification and RFC
 
 Once the merge request is opened, send a message to the [Board mailing list](mailto:board@haskell.foundation) announcing the MR. Post to the [Haskell Discourse](https://discourse.haskell.org/) under the Haskell Foundation topic with the initial text and a link to the MR.