Make README more informative

Update compatibility with the packages and Quantum ESPRESSO,
and provide useful information on how to install and
develop the packge following the aiidateam standards.

Remove also old `todo.md` file.

README.md

@@ -1,6 +1,62 @@
-# aiida-hubbard
+# `aiida-hubbard`
 AiiDA plugin for the Hubbard module of Quantum ESPRESSO.
 The plugin requires HP v7.2 or above and is not compatible with older versions.
 
-# Requirements
-This package depends directly on `aiida-core>=2.0.0` and the `aiida-quantumespresso>=4.0.0` package.
+This is the official AiiDA plugin for the [HP](https://www.sciencedirect.com/science/article/pii/S0010465522001746) code of [Quantum ESPRESSO](https://www.quantum-espresso.org/).
+
+## Compatibility matrix
+
+The matrix below assumes the user always install the latest patch release of the specified minor version, which is recommended.
+
+| Plugin | AiiDA | Python | Quantum ESPRESSO |
+|-|-|-|-|
+| `v0.1.0` | ![Compatibility for v4.0][AiiDA v4.0-pydantic2] |  [![PyPI pyversions][Python v3.9-v3.12]](https://pypi.org/project/aiida-quantumespresso/) | ![Quantum ESPRESSO compatibility][QE v7.2-7.4] |
+
+## Installation
+To install using pip, simply execute:
+
+    pip install git+https://github.com/aiidateam/aiida-hubbard
+
+or when installing from source:
+
+    git clone https://github.com/aiidateam/aiida-hubbard
+    pip install aiida-hubbard
+
+## Pseudopotentials
+Pseudopotentials are installed and managed through the [`aiida-pseudo` plugin](https://pypi.org/project/aiida-pseudo/).
+The easiest way to install pseudopotentials, is to install a version of the [SSSP](https://www.materialscloud.org/discover/sssp/table/efficiency) through the CLI of `aiida-pseudo`.
+Simply run
+
+    aiida-pseudo install sssp
+
+to install the default SSSP version.
+List the installed pseudopotential families with the command `aiida-pseudo list`.
+You can then use the name of any family in the command line using the `-F` flag.
+
+## Development
+
+### Running tests
+To run the tests, simply clone and install the package locally with the [tests] optional dependencies:
+
+```shell
+git clone https://github.com/aiidateam/aiida-hubbard .
+cd aiida-hubbard
+pip install -e .[tests]  # install extra dependencies for test
+pytest -sv tests # run tests
+pytest -sv examples # run examples
+```
+
+You can also use `tox` to run the test set. Here you can also use the `-e` option to specify the Python version for the test run. Example:
+```shell
+pip install tox
+tox -e py39 -- tests/calculations/hp/test_hp.py
+```
+
+### Pre-commit
+To contribute to this repository, please enable pre-commit so the code in commits are conform to the standards.
+Simply install the repository with the `pre-commit` extra dependencies:
+```shell
+cd aiida-hubbard
+pip install -e .[pre-commit]
+pre-commit install
+```