Update helm chart references, release tooling command

Created by: caugustus-sourcegraph

Update the docs to reference the new helm chart version, and fix the release tooling command that was supposed to do this automatically.

Same as https://github.com/sourcegraph/sourcegraph/pull/34441 but correct this time?

Test plan

Doc looks good, and I really ran the release tooling to verify the change this time (instead of just copy-pasting the find / sed).