Add a document on the rules we should follow while managing/reviewing PRs,

and link to it from CONTRIBUTING.md and CODE_OF_CONDUCT.md

CODE_OF_CONDUCT.md

@@ -1,3 +1,7 @@
 # Code of Conduct
 
 Be respectful toward other members of the community. Don't initiate or engage in discussions that are designed to insult, inflame, attack, or incite hate/discrimination/bullying against others. Don't feed the trolls. If we detect any kind of behaviour we consider unacceptable, we reserve the right to ban, block, or remove the involved members from any or all of our communities.
+
+# See Also
+
+- [Rules for managing Pull Requests](PULL_REQUEST_MANAGEMENT.md)

CONTRIBUTING.md

@@ -101,3 +101,7 @@ Finding a good project to start with can be a challenge, because when starting o
   [Coverity]:                                                    https://scan.coverity.com/projects/reactos
   [request-coverity]:                                            https://scan.coverity.com/memberships/new?project_id=reactos
   [commit template]:                                             .gitmessage
+
+# See Also
+
+- [Rules for managing Pull Requests](PULL_REQUEST_MANAGEMENT.md)

PULL_REQUEST_MANAGEMENT.md

@@ -0,0 +1,16 @@
+# Rules for managing Pull Requests
+
+For the sake of trying to maintain an acceptable number of open but idle PRs, the following rules should be considered:
+- If a PR has at least one approval, it can be merged after 1 week of waiting for additional comments.
+  - If the change has at least 3 approvals or you consider it trivial enough, it may be merged right away.
+- If a PR stays in "changes requested" for too long, and there is no indication from the author that they are working on it, it shall be closed.
+  - Rule of thumb: 2 weeks for a small PR. Can be longer if the PR is large.
+  - The PR can be reopened at any point, if you have additional comments, or new changes have been done.
+- If you require a review from a particular person, assign the PR to that person. Don't just rely on the "review requested" feature of GitHub.
+- Remember that PR labels exist. You can assign an appropriate label to a pull request to designate it's scope, grab additional attention or just for extra navigation possibilities.
+- Don't feel obliged to comment everything you see, just for the sake of commenting. Be it on JIRA, GitHub, or even on IRC.
+
+In addition, in order to avoid coming off as rude to helpful contributors, please refrain from:
+- Asking the contributor to do unrelated work
+- Closing without providing a reason
+- Merging with the intention to rewrite that code soon after