admin: update README.md
Merge a PR that changes some `config/foo/org.yaml` and then run the following:
```shell
# Displays what it would do without making changes until you add the confirm flag
-bazel run //admin:update -- --github-token-path ~/path-to-my-token # --confirm
+./admin/update.sh --github-token-path ~/path-to-my-token # --confirm
```
This will default to a dry-run mode, displaying what changes it intends to make without actually updating anything on github.
It will apply the change if you send it the `--confirm` flag.
-It also runs the `bazel test //config:all` unit tests to sanity check the config.
+It also runs `make test` to validate the config.
Assuming everything works the tool should output something like the following:
```console
