update PR_REVIEW with some docs notes (#3994)

* update PR_REVIEW with some docs notes

* adding note about COPPA change

PR_REVIEW.md

@@ -14,6 +14,11 @@ For modules and core platform updates, the initial reviewer should request an ad
 - Review for obvious errors or bad coding practice / use best judgement here.
 - If the change is a new feature / change to core prebid.js - review the change with a Tech Lead on the project and make sure they agree with the nature of change.
 - If the change results in needing updates to docs (such as public API change, module interface etc), add a label for "needs docs" and inform the submitter they must submit a docs PR to update the appropriate area of Prebid.org **before the PR can merge**. Help them with finding where the docs are located on prebid.org if needed. 
+  - Below are some examples of bidder specific updates that should require docs update (in their dev-docs/bidders/bidder.md file):
+    - Add support for GDPR consentManagement module > add `gdpr_supported: true`
+    - Add support for userId module > add `userId: pubCommon, digitrust, newProviderHere`
+    - Add support for video and/or native mediaTypes > add `media_types: video, native`
+    - Add support for COPPA > add `coppa_supported: true`
 - If all above is good, add a `LGTM` comment and request 1 additional core member to review.
 - Once there is 2 `LGTM` on the PR, merge to master
 - Ask the submitter to add a PR for documentation if applicable.