chore(docs): update pull request approval process (#5374)

docs/contributing/process.md

@@ -32,6 +32,11 @@ for the lifecycle of the PR: review, merging, ping on inactivity, close.
 We close pull requests or issues if there is no response from the author for
 a period of time. Feel free to reopen if you want to get back on it.
 
+_Note:_
+Pull requests that are labelled with _size/l_ and above _MUST_ have at least **TWO**
+approvers for it to be merged. Please respect this policy to ensure the quality
+of code in this project.
+
 ### Triggering e2e tests
 
 We have an extensive set of e2e tests that test the integration with *real* cloud provider APIs.