Create `CONTRIBUTING`

Create a `CONTRIBUTING.md` file to provide a guide for contributors. 
This file should include information about how to install the `pre-commit`, for example
   
> **First, install `pre-commit`**
> ```sh
> pip install pre-commit
> ```
> Next, run 
> ```sh
> pre-commit install
> ```
> to install the `pre-commit` hooks