corrected a link.

LearnRedux/Videos.md

@@ -197,7 +197,7 @@ export default rootReducer
     ```
 
 ## Video 13: Displaying the Single Photo Component
-* Polyfills are new ES6 functions cross compiled for old browsers through Babel. [Example for findIndex()][1]
+* Polyfills are new ES6 functions cross compiled for old browsers through Babel. [Example for findIndex()]
 * You can use `findIndex()` to get a certain element of an array
     
     ```jsx
@@ -209,6 +209,6 @@ export default rootReducer
         ...
     }
     ```
-[1](https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex#Polyfill)
+[Example for findIndex()]: https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex#Polyfill
 
 ## Video 14: Displaying and Adding Comments