docs: add Rule Deprecations page (#6156)

* docs: add Rule Deprecations page

* Update docs/maintenance/issues/Rule_Deprecations.md

Co-authored-by: Brad Zacher <brad.zacher@gmail.com>

Co-authored-by: Brad Zacher <brad.zacher@gmail.com>

docs/maintenance/ISSUES.md

@@ -1,6 +1,5 @@
 ---
 id: issues
-sidebar_label: Issues
 title: Issues
 ---
 

docs/maintenance/issues/Rule_Deprecations.md

@@ -0,0 +1,34 @@
+---
+id: rule-deprecations
+title: Rule Deprecations
+---
+
+Sometimes a rule that used to be 👍 does not age well and becomes 👎.
+In the past, these cases have included:
+
+- Overly opinionated and/or stylistic rules that don't represent a universal best practice
+- Renames
+- Rules moved to an external plugin
+
+In these cases, we aim to remove the old rule with minimal user disruption.
+
+## Filing the Issue
+
+Rule deprecations can be filed as a [new issue bypassing templates](https://github.com/typescript-eslint/typescript-eslint/issues/new).
+
+Provide it an `## Overview` containing:
+
+- The rule name & link to its documentation page
+- A clear explanation of why you believe it should be deprecated
+- Whether it exists in popular configs such as `eslint-config-airbnb-typescript` and `eslint-config-standard-with-typescript`
+- Sourcegraph queries showing how often it appears in user configs
+
+> See [#6036](https://github.com/typescript-eslint/typescript-eslint/issues/6036) for examples of those links and queries.
+
+## Timeline
+
+1. In any minor/patch version, add [rule `meta` properties](https://eslint.org/docs/latest/developer-guide/working-with-rules#rule-basics):
+   - `deprecated: true`
+   - `replacedBy`, if applicable
+2. In the next major version, you may delete the rule
+   - If the rule is relatively popular with users, consider leaving a documentation page as a tombstone pointing to the new relevant rule or docs (see [`camelcase`](https://typescript-eslint.io/rules/camelcase/) as an example)

packages/website/sidebars/sidebar.base.js

@@ -67,7 +67,16 @@ module.exports = {
     },
     {
       items: [
-        'maintenance/issues',
+        {
+          collapsible: false,
+          items: ['maintenance/issues/rule-deprecations'],
+          label: 'Issues',
+          link: {
+            id: 'maintenance/issues',
+            type: 'doc',
+          },
+          type: 'category',
+        },
         'maintenance/pull-requests',
         'maintenance/releases',
         'maintenance/versioning',