Mention the RFC project column in docs (#688)

Nothing is automating "ready for review" unfortunately, but the lack of RFC mention seems like a clear miss.

docs/project/evolution.md

@@ -65,8 +65,11 @@ language are well explained, justified, and reviewed by the community.
     [the template](/proposals/template.md).
 
 -   Proposal PRs start out in draft mode. When proposal PRs are ready, click on
-    ["Ready for review"](https://docs.github.com/en/github/collaborating-with-issues-and-pull-requests/changing-the-stage-of-a-pull-request#marking-a-pull-request-as-ready-for-review)
-    in GitHub.
+    ["Ready for review"](https://docs.github.com/en/github/collaborating-with-issues-and-pull-requests/changing-the-stage-of-a-pull-request#marking-a-pull-request-as-ready-for-review),
+    and change the
+    [Proposals project column](https://github.com/carbon-language/carbon-lang/projects/1)
+    to "RFC". The project column should be available as a dropdown under
+    "Projects" on the PR.
 
     -   This will result in a Carbon lead being assigned to review the PR.
 
@@ -129,12 +132,20 @@ issues for longer discussion:
 
 -   When ready, click on
     ["Ready for review"](https://docs.github.com/en/github/collaborating-with-issues-and-pull-requests/changing-the-stage-of-a-pull-request#marking-a-pull-request-as-ready-for-review)
-    in GitHub.
+    in GitHub, and change the
+    [Proposals project column](https://github.com/carbon-language/carbon-lang/projects/1)
+    to "RFC". The project column should be available as a dropdown under
+    "Projects" on the PR.
 
     -   This will result in the PR being assigned to an individual for review.
 
     -   This will also send the proposal as a broad RFC to the community.
 
+    -   While setting the "RFC" project column will also add the "RFC" label,
+        the reverse is not true. Unfortunately, this is currently a limit of
+        GitHub automation. Similarly, Adding the "RFC" project column currently
+        does not set "Ready for review".
+
 -   Address comments where you can and they make sense.
 
 -   If you don't see an obvious way to address comments, that's OK.