improve notes

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## Changelog
 ##### Unreleased
-- Added `Object.prototype.__proto__` polyfill
+- Added [`Object.prototype.__proto__`](https://tc39.es/ecma262/#sec-object.prototype.__proto__) polyfill
+  - It's optional, legacy, and in some cases (mainly because of developers' mistakes) can cause problems, but [some libraries depend on it](https://github.com/denoland/deno/issues/13321), and most code can't work without the proper libraries' ecosystem
   - Only for modern engines where this feature is missed (like Deno), it's not installed in IE10- since here we have no proper way setting of the prototype
   - Without fixes of early implementations where it's not an accessor since those fixes are impossible
   - Only for the global version