Add approval step for product managers

Require MR approval from product managers when
an application limit is added or changed.

doc/development/code_review.md

@@ -99,6 +99,7 @@ with [domain expertise](#domain-experts).
 1. If your merge request includes end-to-end **and** non-end-to-end changes (*3*), it must be **approved
    by a [Software Engineer in Test](https://about.gitlab.com/handbook/engineering/quality/#individual-contributors)**.
 1. If your merge request only includes end-to-end changes (*3*) **or** if the MR author is a [Software Engineer in Test](https://about.gitlab.com/handbook/engineering/quality/#individual-contributors), it must be **approved by a [Quality maintainer](https://about.gitlab.com/handbook/engineering/projects/#gitlab_maintainers_qa)**
+1. If your merge request includes a new or updated [application limit](https://about.gitlab.com/handbook/product/product-processes/#introducing-application-limits), it must be **approved by a [product manager](https://about.gitlab.com/company/team/)**.
 
 - (*1*): Please note that specs other than JavaScript specs are considered backend code.
 - (*2*): We encourage you to seek guidance from a database maintainer if your merge