update regex example to be case insensitive

Author: MartinNowak

README.md

@@ -60,7 +60,7 @@ Using this syntax is also very important because for the changelog generation, t
 git history will be used. Thus _only_ if the Dlang-Bot has detected an issue
 and commented on your PR it can become part of the changelog.
 
-In doubt, you can use e.g. [Regex101](https://regex101.com/r/aI0Rp6/2) to validate your commit message.
+In doubt, you can use e.g. [Regex101](https://regex101.com/r/aI0Rp6/5) to validate your commit message.
 
 ### Nerdy details