Update README.md to include googler post verification steps (#162272)

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [ ] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

Author: reidbaker

dev/conductor/README.md

@@ -96,3 +96,7 @@ For the final step, the user must manually verify that packaging builds have
 finished successfully. The SDK compressed archives will not be available from
 the website until the packaging build has finished. The conductor will produce
 links to the dashboards for monitoring CI builds.
+
+### Post verificaion steps (mostly communication)
+
+Googler instructions for post release documented at go/flutter-release-workflow#notify