docs: update rule README

docs/rules/no-parent-barrel-import.md

@@ -2,7 +2,9 @@
 
 <!-- end auto-generated rule header -->
 
-Forbid a module from importing from parent barrel file. This often leads to runtime error `Cannot read ... of undefined`.
+Forbid a module from importing from parent barrel file, as it often leads to runtime error `Cannot read ... of undefined`.
+
+It resolves the missing circular import check from [`no-self-import`], while being computationally cheap (see [`no-cycle`]).
 
 ## Rule Details
 
@@ -14,7 +16,8 @@ export * from "./bar";
 export * from "./baz";
 
 // foo/bar.ts (cannot read property `X` of undefined)
-import { T } from '..';
+import { T } from '@foo';  // absolute
+import { T } from '..';    // relative
 
 export const X = T.X;
 
@@ -32,7 +35,8 @@ export * from "./bar";
 export * from "./baz";
 
 // foo/bar.ts (relative import for code in `foo/`)
-import { T } from "./baz";
+import { T } from "@foo/baz";  // absolute
+import { T } from "./baz";     // relative
 
 export const X = T.X;
 
@@ -41,3 +45,11 @@ export enum T {
   X = "..."
 }
 ```
+
+## Further Reading
+
+- [Related Discussion](https://github.com/import-js/eslint-plugin-import/pull/2318#issuecomment-1027807460)
+- Rule to detect that module imports itself: [`no-self-import`], [`no-cycle`]
+
+[`no-self-import`]: ./no-self-import.md
+[`no-cycle`]: ./no-cycle.md