Docs: Poetry contributing (#507)

* add info on poetry installation

* add details on just

docs/contributing.qmd

@@ -119,6 +119,26 @@ scoop bucket add extras
 scoop install extras/quarto
 ```
 
+### Package Management
+
+`PyFixest` is using [poetry](https://github.com/python-poetry/poetry).
+
+Please follow the [installation instructions](https://python-poetry.org/docs/#installing-with-the-official-installer) from the poetry documentation.
+
+Afterwards, you can initiate the project environment and install all dependencies by running
+
+```{bash}
+cd path-to-pyfixest
+poetry install
+```
+
+If you type
+```{bash}
+poetry shell
+```
+
+you will see that you have activated a custom poetry environment for pyfixest.
+
 ### Code Style
 
 We use `ruff` and `pre-commit` to ensure a consistent code style.
@@ -141,7 +161,8 @@ and you're ready to go!
 
 There are several command line targets that assist with development included in the
 `justfile`. [Just](https://just.systems/) can be installed to help run these
-command line targets.
+command line targets. Installing `just` is only recommended and not needed for
+development of pyfixest.
 
 On Mac/Linux via [Homebrew](https://formulae.brew.sh/formula/just#default):