Add exercises for ws24

[konradpa]

This adds tweaked exercises for the Hamburg/Rotterdam course to the Exercises page. (https://github.com/lnnrtwttkhn/version-control-course-uhh-eur-ws24/issues/10)

[lnnrtwttkhn]

Thanks @konradpa! Briefly looked over this: Could you remove any reference to WS24 or Hamburg / Rotterdam and generalize this to City Guide or something similar. We can quickly discuss in person what the best label might be, but I would like to use something that generalizes beyond the specific teaching collaboration and semester. This would need to be changes in both the filenames and the content. Please commit the file renaming and any changes inside the files separately. For renaming files, I would use git mv <old-name> <new-name>. Thanks!

[lnnrtwttkhn]

Thanks for the changes in 4a85a60.

• [x] Could you please change this for all other files as well?
• [x] Also, please remove the references to ws24 in the file names and replace with city-guide or something similar. As mentioned above, for renaming, I would use git mv.

Thanks!