Fix broken link (#11)

docs/faq/basics/basic-operations.md

@@ -27,7 +27,7 @@ A good and safe casting example:
 [!code-csharp[Casting](samples/cast.cs)]
 
 [InvalidCastException]: https://docs.microsoft.com/en-us/dotnet/api/system.invalidcastexception
-[this post]: https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/types/how-to-safely-cast-by-using-as-and-is-operators
+[this post]: https://docs.microsoft.com/en-us/dotnet/csharp/how-to/safely-cast-using-pattern-matching-is-and-as-operators
 
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