docs: @putout/plugin-parens: assign

Author: coderaiser

packages/plugin-parens/README.md

@@ -30,6 +30,10 @@ npm i @putout/plugin-parens
 
 ### assign
 
+> The JavaScript exception "invalid assignment left-hand side" occurs when there was an unexpected assignment somewhere. It may be triggered when a single `=` sign was used instead of `==` or `===`.
+>
+> [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Invalid_assignment_left-hand_side)
+
 To disable use:
 
 ```json