Actually include USEFUL examples

https://code2prompt.dev/docs/tutorials/learn_filters/ gives examples like: ``` code2prompt test_dir --include="*.py" --exclude="**/uppercase/*" --include-priority=true code2prompt test_dir --include="*.py" code2prompt test_dir --exclude="*.txt" ``` And then there's a lot of GPT-written word fluff. Instead of that, include USEFUL examples which show: - How to exclude a folder with a given name - How to exclude MULTIPLE patterns - How to exclude the paths specified in .gitignore