Add resource for function borrowing (#4725)

* Update 100-function-borrowing.md

added stackoverflow example

* Update src/data/roadmaps/javascript/content/111-javascript-this-keyword/100-function-borrowing.md

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Co-authored-by: Kamran Ahmed <kamranahmed.se@gmail.com>

src/data/roadmaps/javascript/content/111-javascript-this-keyword/100-function-borrowing.md

@@ -5,3 +5,4 @@ Function borrowing allows us to use the methods of one object on a different obj
 Visit the following resources to learn more:
 
 - [Function borrowing](https://medium.com/@ensallee/function-borrowing-in-javascript-4bd671e9d7b4)
+- [When would I use function borrowing] (https://stackoverflow.com/questions/69892281/when-would-i-use-function-borrowing)