Fixed a typo in instructions for bank-account exercise

"approuch" --> "approach"

Author: Nightlite185

exercises/practice/bank-account/.docs/instructions.append.md

@@ -1,4 +1,4 @@
 # Hints
 
-This exercise requires you to handle data related to currency and money. A normal approuch is to use the [Decimal](https://docs.microsoft.com/en-us/dotnet/api/system.decimal).
+This exercise requires you to handle data related to currency and money. A normal approach is to use the [Decimal](https://docs.microsoft.com/en-us/dotnet/api/system.decimal).
 Note though that you then only store the numeric value of a currency.