docs: update contributor policy docs (#10921)

* docs: update stale PR policy

* docs(readme): add agent friendly badge

COLLABORATOR_GUIDE.md

@@ -39,7 +39,7 @@ At least one maintainer must review and approve the PR before it can be merged.
 If changes are requested, address them in a timely manner. If you are unable to make the changes, communicate that clearly so someone else can pick it up.
 
 > [!IMPORTANT]  
-> We will wait a maximum of 21 days for a response to requested changes before closing the PR. If the PR is closed due to inactivity, it can be reopened if the requested changes are made.
+> We will wait a maximum of 28 days for a response to requested changes before closing the PR as stale. Once closed as stale, we will either address the issue in a maintainer-led PR or open an issue for other contributors to pick up. If the author wants to continue the work, they should re-create the PR from the latest version of the correct target branch, address all feedback provided, and request review from a maintainer.
 
 ## Security Disclosures
 

README.md

@@ -325,6 +325,7 @@
 [![gitter chat](https://img.shields.io/gitter/room/mzabriskie/axios.svg?style=flat-square)](https://gitter.im/mzabriskie/axios)
 [![code helpers](https://www.codetriage.com/axios/axios/badges/users.svg)](https://www.codetriage.com/axios/axios)
 [![Contributors](https://img.shields.io/github/contributors/axios/axios.svg?style=flat-square)](CONTRIBUTORS.md)
+[![Agent Friendly](https://agentfriendlycode.com/api/badge/github/axios/axios.svg)](https://agentfriendlycode.com/repo/32)
 
 </div>