Add link to example repo in exercise

exercises/complexity.qmd

@@ -4,7 +4,7 @@ title: "Complexity"
 
 ### Using `git bisect` to find committed bugs
 
-_The tasks should be done using the test repository **(provide link here)**._
+_The tasks should be done using the test repository <https://gitlab.dkrz.de/generic-software-skills/bisect-example>._
 
 **General information**