update publishing steps (#1427)

Notes taken from when I ran the publishing steps last release cycle.

Co-authored-by: Christopher Radek <Christopher.Radek@microsoft.com>

CONTRIBUTING.md

@@ -198,26 +198,65 @@ pnpm e2e-tests --local-cadl-ranch=/Users/some/dev/cadl-ranch
 
 ## Publishing
 
+### Prerequisites
+
+1. Install the GitHub CLI and configure your account. Some of the tools use your GitHub account.
+2. Check that validation of the `typespec-next` branch is green in [pipelines](https://dev.azure.com/azure-sdk/public/_build?definitionId=6143&_a=summary).
+   1. **Note**: Anytime a new PR is merged during the release process, make sure this validation is green.
+3. Verify that the CodeGen nightly [builds](https://dev.azure.com/azure-sdk/public/_dashboards/dashboard/ef641981-29b5-4a67-9e8f-1e4ae2fe4894) are green.
+   1. **Note**: Check with codegen owners if a build is red due to a change unrelated to the TypeSpec release.
+
+### Steps
+
 Do the following to publish a new release:
 
 1. Announce to coworkers on Teams in TypeSpec Engineering channel that you will
    be publishing and that they should hold off on merging until the process
    is complete.
 
 2. Make sure your working copy is clean and you are up-to-date and on the
-   main branch.
+   main branch (both typespec-azure and core should point to main).
 
-3. Run `pnpm prepare-publish` to stage the publishing changes.
+3. Generate release notes for TypeSpec once the full list of changes are in.
 
-If it works you'll get a message like this:
+   1. In your fork of the core (typespec) repo, run `npx chronus changelog --policy typespec > out.md`.
+   1. Create a new entry in `docs/release-notes` for this release and paste the contents of `out.md` into the new file. Reorganize the file to have the following sections in order: _Breaking Changes_, _Deprecations_, _Features_, and _Bug Fixes_. Skip the section if there are no entries in it. Also add a blurb above these sections for any especially notable updates.
+      Example PR: https://github.com/microsoft/typespec/pull/4102
 
-```
-Success! Push publish/kvd01q9v branches and send PRs.
-```
+4. Generate release notes for TypeSpec Azure once the full list of changes are in.
+
+   1. In your fork of the typespec-azure repo, run `npx chronus changelog --policy typespec-azure > out.md`.
+   1. Create a new entry in `docs/release-notes` for this release and paste the contents of `out.md` into the new file. Reorganize the file to have the following sections in order: _Breaking Changes_, _Deprecations_, _Features_, and _Bug Fixes_. Skip the section if there are no entries in it. Also add a blurb above these sections for any especially notable updates.
+      Example PR: https://github.com/Azure/typespec-azure/pull/1306
+
+5. Once all PRs are merged, update TypeSpec-Azure core submodule (things will run more smoothly if TypeSpec-Azure core points to HEAD of TypeSpec).
+
+   1. Can [trigger](https://github.com/Azure/typespec-azure/network/updates/18647270/jobs) dependabot via `Insights > Dependency graph > Dependabot`.
+
+6. Double-check that typespec-azure and core submodules are both up to date with `upstream/main`.
+
+7. Regenerate documentation via `pnpm regen-docs` in TypeSpec-Azure.
+
+8. Run `pnpm prepare-publish` in TypeSpec-Azure repo to stage the publishing changes.
+
+   - This creates `publish/xxxxxx` branches for TypeSpec-Azure and TypeSpec repos.
+   - If it works you'll get a message like this: `Success! Push publish/kvd01q9v branches and send PRs.`
+
+   - Double-check that updated version numbers are correct. Running the tool multiple times will increment the version number multiple times as well.
+
+9. Push and merge TypeSpec (core) PR.
+
+10. Update core submodule to use `main` in TypeSpec-Azure `publish/` branch and push/merge PR.
+
+11. Make sure release pipeline completed and packages are on NPM.
+
+### Followups
 
-4. Follow steps 4-9 in [making a cross-cutting change across both
-   repos](#making-a-cross-cutting-change-across-both-repos) to send PRs from
-   the generated `publish/<unique_id>` branches and merge them.
+1. Upgrade https://github.com/Azure/azure-rest-api-specs to use new versions of TypeSpec.
+   1. Example PR: https://github.com/Azure/azure-rest-api-specs/pull/30122
+1. Upgrade https://github.com/Azure/cadl-ranch to use new versions of TypeSpec.
+   1. Example PR: https://github.com/Azure/cadl-ranch/pull/668
+1. Send an email to the `TypeSpec Partners` group announcing the release.
 
 **NOTE**: The reason for step 1 to ask for folks to avoid merging while
 publishing is in progress is that any changes merged to the repo while the