[llvm] Document the community RFC process (PR #116386)

[David Blaikie via llvm-commits]

================
@@ -0,0 +1,80 @@
+=================================
+Request For Comment (RFC) process
+=================================
+
+.. contents::
+   :local:
+   :depth: 1
+
+Introduction
+============
+Substantive changes to LLVM projects need to be acceptable to the wider
+community, which requires gaining community consensus to adopt the changes.
+This is done by posting an RFC and obtaining feedback about the proposal.
+
+Process
+=======
+
+Writing an RFC
+--------------
+The process begins with writing a proposal for the changes you'd like to see
+made. The proposal should include:
+
+* a high-level overview of what changes are being proposed,
+* information detailing the motivation for why the changes are being proposed,
+* detailed information the proposed changes and how they impact different parts
----------------
dwblaikie wrote:

Maybe this would be "detailed description of the proposed changes"?

If bullet one already says "an overview of the proposed changes" perhaps this bullet point could focus on the "impact" issue and be reduced to "* the impact on different parts of the project"?

https://github.com/llvm/llvm-project/pull/116386