docs: Various improvements to the contributor guide

docs/development/contributing/ide.md

@@ -5,11 +5,38 @@ This page contains some recommendations for configuring popular IDEs.
 
 ## Visual Studio Code
 
+### Python environment
+
 Make sure to configure VSCode to use the virtual environment created by the Makefile.
+VSCode will prompt you to do this automatically once the Makefile creates the `.venv` folder.
+You can also run the `Python: Select Interpreter` command to manually configure the workspace to use the local `.venv` interpreter.
+
+You can use the `Python: Create Terminal` command to easily launch a terminal instance that has the virtual environment loaded.
+
+### Line lengths
+
+We use 88 characters for Python code and 100 characters for Rust code. If you want VSCode to show you rulers at those points, add the following settings to your `.vscode/settings.json`:
+
+```json
+{
+    "[python]": {
+        "editor.rulers": [
+            88
+        ],
+    },
+    "[rust]": {
+        "editor.rulers": [
+            100
+        ],
+    },
+}
+```
 
-In addition, the extensions below are recommended.
+### Extensions
 
-### rust-analyzer
+We recommend using the following VSCode extensions to aid your development experience.
+
+#### rust-analyzer
 
 If you work on the Rust code at all, you will need the [rust-analyzer](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust-analyzer) extension. This extension provides code completion for the Rust code.
 
@@ -21,11 +48,22 @@ For it to work well for the Polars code base, add the following settings to your
 }
 ```
 
-### Ruff
+#### Ruff
+
+We use the Ruff linter and formatter on our Python code. The [Ruff](https://marketplace.visualstudio.com/items?itemName=charliermarsh.ruff) extension will help you conform to the formatting requirements of the Python code.
+
+If you want to configure Ruff to format automatically on save, add the following settings to your `.vscode/settings.json`:
+
+```json
+{
+    "[python]": {
+        "editor.formatOnSave": true,
+        "editor.defaultFormatter": "charliermarsh.ruff",
+    }
+}
+```
 
-The Ruff extension will help you conform to the formatting requirements of the Python code.
-We use both the Ruff linter and formatter.
-It is recommended to configure the extension to use the Ruff installed in your environment.
+You should also configure the extension to use the Ruff installed in your virtual environment.
 This will make it use the correct Ruff version and configuration.
 
 ```json

docs/development/contributing/index.md

@@ -152,7 +152,7 @@ The user guide is maintained in the `docs/user-guide` folder. Before creating a
 
 The user guide is built using [MkDocs](https://www.mkdocs.org/). You install the dependencies for building the user guide by running `make requirements` in the root of the repo.
 
-Run `mkdocs serve` to build and serve the user guide, so you can view it locally and see updates as you make changes.
+Run `mkdocs serve` from inside the virtual environment to build and serve the user guide, so you can view it locally and see updates as you make changes.
 
 #### Creating a new user guide page
 
@@ -228,6 +228,7 @@ From the `py-polars` directory, run `make fmt` to make sure your additions pass
 Polars uses Sphinx to build the API reference.
 This means docstrings in general should follow the [reST](https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html) format.
 If you want to build the API reference locally, go to the `py-polars/docs` directory and run `make html SPHINXOPTS=-W`.
+By default, this uses only one thread. To speed it up, run `make html SPHINXOPTS="-W -j auto"` to use all available cpus.
 The resulting HTML files will be in `py-polars/docs/build/html`.
 
 New additions to the API should be added manually to the API reference by adding an entry to the correct `.rst` file in the `py-polars/docs/source/reference` directory.