Emphasize use of runnerToken in Helm chart
What does this MR do?
This MR updates https://docs.gitlab.com/runner/install/kubernetes.html to emphasize the use of runnerToken instead of the deprecated runnerRegistrationToken.
Why was this MR needed?
To avoid confusing users by suggesting a workflow that is now deprecated.
What's the best way to test this MR?
- https://main-runner-4150.docs.gitlab-review.app/runner/install/kubernetes.html#required-configuration
- https://main-runner-4150.docs.gitlab-review.app/runner/install/kubernetes.html#store-registration-tokens-or-runner-tokens-in-secrets