README: Add more contributing guidelines

README.md

@@ -40,7 +40,9 @@ not recommended unless for development purposes. It depends on patches
 that are found in the `org.flatpak.Builder` flatpak package
 and on external tools.
 
-For development purposes it can be installed with:
+## Contributing
+
+For development purposes the project can be installed with:
 
 ```bash
 git clone https://github.com/flathub/flatpak-builder-lint
@@ -52,16 +54,18 @@ poetry run flatpak-builder-lint --help
 After making changes to the code or any dependencies run
 `poetry lock --no-update` to regenerate the lockfile (when adding
 or changing dependency versions) and `poetry install --sync` to
-synchronise the virtual environment. The virtual enviroment can be
-removed with `poetry env remove flatpak-builder-lint-xxxxxxxx-py3.xx`
+synchronise the virtual environment.
+
+The virtual enviroment can be removed with
+`poetry env remove flatpak-builder-lint-xxxxxxxx-py3.xx`
 (check the environment name with `poetry env list`).
 
 The following Python dependencies are needed to run
 `jsonschema^4.19.1, requests^2.32.2, requests-cache^1.2.1, lxml^5.2.2,
-sentry-sdk^2.8.0, PyGObject=^3.48.2`. Additionally `poetry-core>=1.0.0`
+sentry-sdk^2.8.0, PyGObject^3.48.2`. Additionally `poetry-core>=1.0.0`
 is necessary to build.
 
-Additionally the following tools or packages must be installed:
+Additionally the following system dependencies must be installed:
 
 - `libgirepository1.0-dev, gir1.2-ostree-1.0`
 - `flatpak-builder` for validating flatpak-builder manifests
@@ -73,6 +77,24 @@ exec flatpak run --branch=stable --command=appstreamcli org.flatpak.Builder ${@}
 ```
 - `desktop-file-validate` to validate desktop files
 
+Debiab/Ubuntu:
+
+```
+# apt install appstream flatpak-builder libgirepository1.0-dev gir1.2-ostree-1.0 libcairo2-dev desktop-file-utils
+```
+
+ArchLinux:
+
+```
+# pacman -S --needed appstream flatpak-builder desktop-file-utils ostree glib2
+```
+
+Fedora:
+
+```
+# dnf install appstream flatpak-builder desktop-file-utils ostree-libs glib2-devel cairo-devel
+```
+
 [Ruff](https://docs.astral.sh/ruff/installation/) is used to lint and
 format code. [MyPy](https://mypy.readthedocs.io/en/stable/getting_started.html)
 is used to check Python types. To run them:
@@ -108,7 +130,7 @@ to run tests:
 poetry run pytest -v tests
 ```
 
-### Usage
+## Usage
 
 ```
 usage: flatpak-builder-lint [-h] [--version] [--exceptions] [--appid APPID] [--cwd] [--ref REF] {builddir,repo,manifest,appstream} path