[Docs] Clarify new proposal process (#689)

This update adds clarification to the new proposal management. We're
going to make an effort to work through our backlog of new proposals and
get them all merged in over the next couple weeks, and we're using this
process as our guide.

Author: llvm-beanz

docs/Process.md

@@ -110,12 +110,21 @@ proposal header should be updated to include a link to the Discord post.
 
 #### Merging a New Proposal
 
-The bar for a proposal to be merged should be kept low. Ideally a PR introducing
-a new proposal should be reviewed for obvious mistakes (typos, grammar, etc),
-and general alignment with project goals and direction. If the proposal aligns
-with the goals and direction, it should be merged as **Under Consideration**,
-and the authors should file issues tracking the work to flesh out and complete
-the detailed design.
+The bar for a proposal to be merged should be kept low. The proposal must have a
+sponsor prior to being merged, and must be approved by the sponsor. A PR
+introducing a new proposal should be reviewed for obvious mistakes (typos,
+grammar, etc). Reviewers may provide feedback on aspects of the design, however
+the author(s) need not address all feedback in the PR before merging. Filing an
+issue to follow-up on comments from the initial PR is an acceptable response to
+feedback and should be done by the author(s) when resolving comments on the PR.
+
+New proposals should be merged as **Under Consideration**. After assigning a
+number and merging the PR the author(s) should file issues tracking the work to
+flesh out and complete the detailed design.
+
+PRs introducing new proposals for language features will be reviewed at the
+[Design Meeting](/docs/DesignMeeting.md). PRs introducing new proposals for
+DirectX or DXIL features will be reviewed by Microsoft on a regular cadence.
 
 #### Completing the Detailed Design