message: Move the milestoning step to be done while making the beta rollup.
diff: @@ -27,12 +27,7 @@ Getting a PR backported to the beta branch involves the following process:
  4. Open a PR **against the beta branch** with a title that starts with `[beta]` (so reviewers can see its specialness).
  5. List all of the PRs being backported in the PR description.
  [Here's an example](https://github.com/rust-lang/rust/pull/64097).
  -
  -4. A reviewer (typically from the release team) needs to verify that the backport looks correct and that it's submitted to the beta branch.
  - They will then approve with `@bors r+ rollup=never` (to avoid it being rolled up on accident).
  - If the author of the PR has r+ rights, and has not made significant changes while backporting, they can also self-approve the PR.
  -
  -5. Go through all of the PRs being backported and:
  + 6. Go through all of the PRs being backported and:
  * Change the milestone to the correct value for the beta release.
  * Remove the `beta-nominated` label.
  @@ -40,6 +35,13 @@ Getting a PR backported to the beta branch involves the following process:
  If there are a lot of PRs, this can be done quickly by opening the [nominated + accepted][nominated-plus-accepted] query, check all the PRs being backported, and use the "Milestones" and "Label" drop-downs to modify multiple PRs in bulk.
  + This last step can be done before or after the beta PR has been merged, though it can be easy to forget if you wait for it to be merged.
  +
  +4. A reviewer (typically from the release team) needs to verify that the backport looks correct and that it's submitted to the beta branch.
  + They will then approve with `@bors r+ rollup=never` (to avoid it being rolled up on accident).
  + If the author of the PR has r+ rights, and has not made significant changes while backporting, they can also self-approve the PR.
  +
  +
  In summary, there are three states that a PR can go through:
  1. `beta-nominated`: Needs the team's attention.
  2. `beta-nominated` + `beta-accepted`: Waiting to be backported.
  