(Infra) Make infra changes to cleanup project and simplify its maintenance (#4531)

* Update readme, add stale bot, add issue template, add pull request template

* Update copy from Alamofire

.github/issue_template.md

@@ -0,0 +1,33 @@
+> ℹ Please fill out this template when filing an issue.
+> All lines beginning with an ℹ symbol instruct you with what info we expect. You can delete those lines once you've filled in the info.
+>
+> Per our [*CONTRIBUTING guidelines](https://github.com/AFNetworking/AFNetworking/blob/master/CONTRIBUTING.md), we use GitHub for
+> bugs and feature requests, not general support. Other issues should be opened on Stack Overflow with the tag `afnetworking`.
+>
+> Please remove this line and everything above it before submitting.
+
+* [ ] I've read, understood, and done my best to follow the [*CONTRIBUTING guidelines](https://github.com/AFNetworking/AFNetworking/blob/master/CONTRIBUTING.md).
+
+## What did you do?
+
+ℹ Please replace this with what you did.  
+
+## What did you expect to happen?
+
+ℹ Please replace this with what you expected to happen.  
+
+## What happened instead?
+
+ℹ Please replace this with of what happened instead.  
+
+## AFNetworking Environment
+
+**AFNetworking version:**
+**Xcode version:**
+**Swift version:**
+**Platform(s) running AFNetworking:**
+**macOS version running Xcode:**
+
+## Demo Project
+
+ℹ Please link to or upload a project we can download that reproduces the issue.

.github/pull_request_template.md

@@ -0,0 +1,13 @@
+### Issue Link :link:
+<!-- What issue does this fix? If an issue doesn't exist, remove this section. -->
+
+### Goals :soccer:
+<!-- List the high-level objectives of this pull request. -->
+<!-- Include any relevant context. -->
+
+### Implementation Details :construction:
+<!-- Explain the reasoning behind any architectural changes. -->
+<!-- Highlight any new functionality. -->
+
+### Testing Details :mag:
+<!-- Describe what tests you've added for your changes. -->

.github/stale.yml

@@ -0,0 +1,33 @@
+# Configuration for probot-stale - https://github.com/probot/stale
+
+# Number of days of inactivity before an Issue or Pull Request becomes stale
+daysUntilStale: 14
+
+# Number of days of inactivity before a stale Issue or Pull Request is closed
+daysUntilClose: 7
+
+# Issues or Pull Requests with these labels will never be considered stale
+exemptLabels:
+  - "support"
+  - "bug"
+  - "security"
+
+# Label to use when marking as stale
+staleLabel: stale
+
+# Comment to post when marking as stale. Set to `false` to disable
+markComment: >
+  This issue has been marked as stale because it has not had
+  recent activity. It will be closed if no further activity occurs. 
+
+# Comment to post when removing the stale label. Set to `false` to disable
+unmarkComment: false
+
+# Comment to post when closing a stale Issue or Pull Request. Set to `false` to disable
+closeComment: >
+  This issue has been auto-closed because there hasn't been any activity for at least 21 days.
+  However, we really appreciate your contribution, so thank you for that! 🙏
+  Also, feel free to [open a new issue](https://github.com/AFNetworking/AFNetworking/issues/new) if you still experience this problem 👍.
+
+# Limit to only `issues`
+only: issues

README.md

@@ -16,7 +16,6 @@ Perhaps the most important feature of all, however, is the amazing community of
 
 - [Download AFNetworking](https://github.com/AFNetworking/AFNetworking/archive/master.zip) and try out the included Mac and iPhone example apps
 - Read the ["Getting Started" guide](https://github.com/AFNetworking/AFNetworking/wiki/Getting-Started-with-AFNetworking), [FAQ](https://github.com/AFNetworking/AFNetworking/wiki/AFNetworking-FAQ), or [other articles on the Wiki](https://github.com/AFNetworking/AFNetworking/wiki)
-- Check out the [documentation](http://cocoadocs.org/docsets/AFNetworking/) for a comprehensive look at all of the APIs available in AFNetworking
 
 ## Communication