update readme

README.md

@@ -9,7 +9,8 @@ has an improved API.
 
 ## Requirements & Installation
 
-pyrad requires Python 3.7 or later.
+pyrad requires Python 3.7 or later. Currently no external dependencies are
+needed to use pyrad3.
 
 ```cli
 # Install from pypi
@@ -25,6 +26,53 @@ poetry install --no-dev # for usage; without optional dev dependencies
 poetry install # for development
 ```
 
+## Development
+
+pyrad3 usese quite a lot of linters and development tools:
+
+- coveralls
+- black
+- poetry
+- pytest
+  - pytest-black
+  - pytest-cov
+  - pytest-flake8
+  - pytest-isort
+  - pytest-mypy
+  - pytest-pylint
+- tox
+- sphinx
+
+This project uses poetry as it packaging and dependency management tool. The
+configuration is done via `pyproject.toml`. To install this package with `pip
+install`, a pip version greater than `19.0` is required.
+
+When poetry is installed, the development dependencies can be installed with
+`poetry install --no-root`. Omitting the `--no-root` parameter will additionally
+install pyrad3 itself.
+
+
+### with nix
+
+
+### Generating the documentation
+
+Sphinx is used for the documentation. It can be either run directly with
+` ` or with `make` (requires `gnumake` to be installed.)
+
+TODO: no documentation yet.
+
+### Running tests locally
+
+pyrad3 comes with a tox configuration (check the `[tool.tox]` section in
+./pyproject.) Tox will set up test environments for all supported python
+versions and run them automatically.
+
+<!-- TODO: is this correct? -->
+It is necessary that the python versions are installed otherwise tox will fail.
+To execute a test with a single python version run `tox -e $version`, e.g.
+`tox -e py38`.
+
 ## License
 
 pyrad3 is distributed under the terms of both the MIT License and the Apache