Changed `ruff.toml` so `ruff` uses Python 3.13 when checking files in `tests/` and `docs/`.

Created a `pre-commit` hook which synchronises examples in `README.rst` with examples in `examples`.

…admes-usage-example

Created a `pre-commit` hook to update examples in `README`

Created a `pre-commit` hook which synchronises examples in `README.rst` with examples in examples.

Closes #39

Fixed `readme-example-updater` `pre-commit` hook to trigger when examples are updated.

Improved the `readme-example-updater` `pre-commit` hook to raise a warning when including non-existent example files in `README.rst`.

Cleaned examples up by removing unused imports, adding docstrings, renaming files for better readability and adding a simpler example for double button set-ups.

Reverted `examples/button_handler_simpletest.py` rename so that `pytest` does not test it.

Updated docs to use the new example paths and include the new exmple.

Cleaned examples up by:
- Changing file names.
- Removing unused imports.
- Adding a short description of the example in each of the files' docstring.
- Creating a simpler two button set-up usage example.
- Improving the `readme-example-updater` `pre-commit` hook to raise a warning when a non-existent file is included in `README.rst`.
- Fixing the `readme-example-updater` `pre-commit` hook to trigger when examples are updated.

Closes #43