Update part2a.md

Change Medium source to author's personal blog -- Medium article can sometimes be paywalled.

Author: vmarklynn

src/content/2/en/part2a.md

@@ -348,7 +348,7 @@ As such, one way to define the row generation without getting errors is:
 
 This is, however, **not recommended** and can create undesired problems even if it seems to be working just fine.
 
-Read more about this in [this article](https://robinpokorny.medium.com/index-as-a-key-is-an-anti-pattern-e0349aece318).
+Read more about this in [this article](https://robinpokorny.com/blog/index-as-a-key-is-an-anti-pattern/).
 
 ### Refactoring Modules