Merge branch '3.6.x' into mergify/bp/3.6.x/pr-3775

CONTRIBUTING.md

@@ -12,7 +12,7 @@
 
 5. You can peruse the [good-first-issues](https://github.com/chipsalliance/chisel3/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22) for easy tasks to start with. Another easy thing to start with is doing your own pass of the [website](https://www.chisel-lang.org/chisel3/docs/introduction.html) looking for typos, pages missing their titles, etc. The sources for the website are [here](https://github.com/chipsalliance/chisel3/tree/master/docs).
 
-6. Please make your PRs against the `master` branch. The project admins, when reviewing your PR, will decide which stable version (if any) your change should be backported to. The backports will be opened automatically on your behalf once your `master` PR is merged.
+6. Please make your PRs against the `main` branch. The project admins, when reviewing your PR, will decide which stable version (if any) your change should be backported to. They will apply the appropriate `milestone` marker which controls which branches the backport will be opened to. The backports will be opened automatically on your behalf once your `main` PR is merged.
 
 7. If your backport PR(s) get labeled with `bp-conflict`, it means they cannot be automatically be merged. You can help get them merged by openening a PR against the already-existing backport branch (will be named something like `mergify/bp/3.5.x/pr-2512`) with the necessary cleanup changes. The admins will merge your cleanup PR and remove the `bp-conflict` label if appropriate.