Remove 'example' app from backend

[XanderVertegaal]

The directory backend/example (and everything in it) is not needed and should be removed.

This is a good way to practice using Git.

You will need to know the following Git commands. Study them if you have not done so yet: git clone, git fetch, git status, git branch, git checkout, git add, git commit, git push.

1. Clone the ParsePort repository to your local machine.
2. Go to the develop branch and fetch the latest version.
3. Check that you are up to date with the latest version (with git status).
4. Create a new local branch called feature/remove-example.
5. Remove the backend/example directory.
6. Add your changes to the current commit.
7. Commit your changes.
8. Push your commit to remote.
9. On GitHub, create a pull request (from your branch to develop)
10. Assign me as a reviewer.
11. Refer to this issue by writing Closes # followed by the number of this issue.
12. Wait until the review is complete.
13. Make changes if necessary.
14. Click the 'Merge' button if your pull request has been accepted.

Feel free to ask me if anything is unclear!

Good luck!