Improve the README.

Author: nedtwigg

python/README.md

@@ -1,13 +1,16 @@
 The python implementation is under construction. It makes use of PEP 695, so you must use Python 3.12 or later.
 
-Dependencies are managed using poetry
+Dependencies are managed using poetry, which you can install here.
 - https://python-poetry.org/docs/#installing-with-the-official-installer
+- then cd into `selfie-lib` and run `poetry install`
 
-Testing via pytest (built-in to the VSCode Python plugin)
-- https://marketplace.visualstudio.com/items?itemName=ms-python.python
+Our CI server runs three checks in the `selfie-lib` directory.
+
+- `poetry run pytest -vv` this runs the tests (`-vv` makes nice output)
+- `poetry run pyright` this does type checking
+- `poetry run ruff check` this checks formatting
 
-Types are declared using [PEP 695](https://peps.python.org/pep-0695/), and checked via pyright
-- https://marketplace.visualstudio.com/items?itemName=ms-pyright.pyright
+For the IDE we use VSCode. Make sure to open the `python` directory, not the parent `selfie`. Receommended VSCode plugins:
 
-Formatting via ruff
-- https://marketplace.visualstudio.com/items?itemName=charliermarsh.ruff
+- https://marketplace.visualstudio.com/items?itemName=ms-python.python
+- https://marketplace.visualstudio.com/items?itemName=charliermarsh.ruff