New: Allow plugins to define rule replacements

designs/2021-plugin-rule-replacements/README.md

@@ -0,0 +1,75 @@
+- Repo: eslint/eslint, eslint/eslintrc
+- Start Date: 2021-01-23
+- RFC PR: (to be filled in)
+- Authors: mykhalov
+
+# Allow plugins to define rule replacements
+
+## Summary
+
+Provide better error message for removed rules by allowing plugins to define rule replacements.
+
+## Motivation
+
+ESLint provides great developer experience around removed rules:
+
+```
+  1:1  error  Rule 'generator-star' was removed and replaced by: generator-star-spacing  generator-star
+```
+
+Until now this hasn't been the case with plugins:
+
+```
+  1:1  error  Definition for rule '@typescript-eslint/camelcase' was not found  @typescript-eslint/camelcase
+```
+
+Although `@typescript-eslint/camelcase` [has been removed in favour of another rule](https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/camelcase.md), there is no way for the plugin to explain this.
+
+## Detailed Design
+
+When reading plugin definition, look for `"replacements"` property next to `"rules"`:
+
+```
+module.exports = {
+    rules,
+    replacements: {
+        rules: {
+            foo: ['bar']
+        }
+    }
+}
+```
+
+If exists, propagate this property to error reporting. When constructing error message, look into plugin replacements before looking into to ESLint replacements.
+
+## Documentation
+
+This should be documented in [Developer Guide](https://eslint.org/docs/developer-guide/working-with-plugins).
+
+## Drawbacks
+
+None at the moment.
+
+## Backwards Compatibility Analysis
+
+No effect on backwards compatibility.
+
+## Alternatives
+
+None at the moment.
+
+## Open Questions
+
+None at the moment.
+
+## Help Needed
+
+None at the moment.
+
+## Frequently Asked Questions
+
+None at the moment.
+
+## Related Discussions
+
+Adding deprecation message to ESLint itself ([#1549](https://github.com/eslint/eslint/issues/1549)).