docs(code-review): recommend using with manual triggers

[Pertempto]

We should update our examples to show manual triggers for the code review bot. If you run it on every commit, it becomes very noisy and unhelpful.

Here is an example of an attempt to run it manually with GitHub actions. Not sure yet if it will work.

For the GitLab CI/CD example, all we need to add is when: manual

We also need to document this change.

[Pertempto]

CC @bambam955