Some missing tasks in the release

Realised there were a couple of steps missing
from the release checklist.

docs/governance/templates/release_issue.md

@@ -11,6 +11,8 @@ and copy it into a release issue. Fill in relevent values, found inside {}
 - [ ] Any issues in the current milestone that are not closed, move to next milestone.
 - [ ] Run `make gen-changelog` to generate the CHANGELOG.md
 - [ ] Ensure the [helm `tag` value][values] is correct (should be the {version} if a full release, {version}.rc if release candidate)
+- [ ] Remove all instances of "⚠️⚠️⚠️ **This is currently a development feature and has not been released** ⚠️⚠️⚠️"
+- [ ] If full release, update install docs with the new release version
 - [ ] Create PR with these changes, and merge them with approval
 - [ ] If full release, close the current milestone.
 - [ ] Confirm local git remote `upstream` points at `git@github.com:GoogleCloudPlatform/agones.git`
@@ -19,11 +21,13 @@ and copy it into a release issue. Fill in relevent values, found inside {}
 - [ ] Create a release with the [release template][release-template]
   - [ ] Make a `tag` with the release version.
   - [ ] Attach all assets found in the `release` folder to the release.
+- [ ] Send an email to the [mailing list][list] with the release details (copy-paste the github release)
 - [ ] If full release, then increment the `base_version` in [`build/Makefile`][build-makefile]
-- [ ] Ensure the [the helm `tag` value][values] is the same at the above `base_version`
+- [ ] Ensure the [the helm `tag` value][values] is the same as the above `base_version`
 - [ ] Create PR with these changes, and merge them with approval
-- [ ] Close this issue. *Congratulations!* - the release is now complete! :tada: :clap: :smile: :+1: 
+- [ ] Close this issue. *Congratulations!* - the release is now complete! :tada: :clap: :smile: :+1:
 
 [values]: https://github.com/GoogleCloudPlatform/agones/blob/master/install/helm/agones/values.yaml#L33
+[list]: https://groups.google.com/forum/#!forum/agones-discuss
 [release-template]: https://github.com/GoogleCloudPlatform/agones/blob/master/docs/governance/templates/release.md
-[build-makefile]: https://github.com/GoogleCloudPlatform/agones/blob/master/build/Makefile
+[build-makefile]: https://github.com/GoogleCloudPlatform/agones/blob/master/build/Makefile