docs: Update contributing guidelines

CONTRIBUTING.md

@@ -48,16 +48,17 @@ The first time you run `hatch shell` the environment will be created and activat
 >
 > This will make hatch set up its environments within the current working directory under `.venv`.
 
-Alternatively, if you prefer to manage your virtual environments differently, you can install the package for development using, for example:
+Alternatively, if you prefer to manage your virtual environments yourself, you can install the package for development using, for example:
 
 ```sh
 python -m venv .venv
+source ./.venv/bin/activate
 pip install -e '.[dev,test,docs]'
 ```
 
 For all pull requests, linting and unit tests are automatically run using the [GitHub Actions](https://docs.github.com/en/actions) Continuous Integration service. However, you are still encouraged to run these checks locally before pushing code to a PR.
 
-## Linting and formatting
+## Linting and Formatting
 
 We use [ruff](https://docs.astral.sh/ruff/) for style checking. Run `ruff check .` or:
 
@@ -71,11 +72,7 @@ Ruff can fix a lot of errors itself. Run `ruff check --fix .` or:
 hatch run fix
 ```
 
-Ruff includes a formatter that mimics [black](https://black.readthedocs.io/en/stable/). To automatically reformat your code, you can use `ruff format .` or:
-
-```sh
-hatch run format
-```
+Ruff includes a formatter that mimics [black](https://black.readthedocs.io/en/stable/). To automatically reformat your code, you can use `ruff format {source_file}`.
 
 We use [pre-commit](https://github.com/pre-commit/pre-commit) to make sure the coding style is enforced. You first need to install pre-commit and the corresponding git commit hooks: