Update CONTRIBUTING.md

Signed-off-by: Marijn van Wezel <96489967+marijnvanwezel@users.noreply.github.com>

.github/CONTRIBUTING.md

@@ -24,9 +24,77 @@ In your bug report, you should provide the following:
 * What you expected would happen
 * What actually happens
 * Steps to reproduce
-** Be specific!
-** Give sample code if possible.
-** Include the version of PHP and php-cypher-dsl.
+  * Be specific!
+  * Give sample code if possible.
+  * Include the version of PHP and php-cypher-dsl.
 
 You should only report bugs for versions of php-cypher-dsl that [are supported](https://github.com/neo4j-php/php-cypher-dsl/blob/main/LIFECYCLE.md). Please only report bugs if you are using a php-cypher-dsl with a [compatible version of PHP](https://github.com/neo4j-php/php-cypher-dsl/blob/main/LIFECYCLE.md).
 
+## Proposing new features
+
+Feel free to propose a new feature by [opening an issue for it](https://github.com/neo4j-php/php-cypher-dsl/issues/new?template=missing_feature_request.md).
+
+## Workflow for pull requests
+
+1. Fork the repository.
+1. Create a new branch.
+   1. If you are **implementing new functionality**, create your branch from `development`.
+   1. If you are **fixing a bug**, create your branch from the oldest branch that is [supported](https://github.com/neo4j-php/php-cypher-dsl/blob/main/LIFECYCLE.md).
+1. Implement your change and add tests for it.
+1. Make sure the test suite passes.
+1. Make sure that the code complies with the coding guidelines (see below).
+1. Submit your pull request!
+
+Some things to keep in mind:
+
+* Make sure that you have [configured a user name and email address](https://git-scm.com/book/en/v2/Getting-Started-First-Time-Git-Setup) for use with Git.
+* Keep backwards compatibility breaks to a minimum.
+* You are encouraged to [sign your commits](https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits) with GPG.
+
+## Branching model
+
+The branching model used by this project is [gitflow](https://nvie.com/posts/a-successful-git-branching-model/), with the following changes/additions:
+
+1. Feature branches must follow the naming convention `feature/*`.
+1. The name of a feature branch should reflect the feature added (e.g. `feature/match-support` instead of `feature/feature-1`).
+1. Release branches must follow the naming convention `release/x.y`.
+1. Hotfix branches must follow the naming convention `hotfix/x.y.z`.
+1. Hotfix branches must branch off from the oldest branch that is [supported](https://github.com/neo4j-php/php-cypher-dsl/blob/main/LIFECYCLE.md).
+1. Right before a new **major** version is released, a *support* branch is created from `main`.
+1. Support branches must follow the naming convention `support/x.y`, where `x.y` is the most recent minor release.
+
+## Coding guidelines
+
+This project comes with a [configuration file](https://github.com/neo4j-php/php-cypher-dsl/blob/main/.php-cs-fixer.dist.php) for php-cs-fixer that you can use to format your code:
+
+```
+$ php vendor/bin/php-cs-fixer fix --config .php-cs-fixer.dist.php
+```
+
+This project uses PHPStan for static analysis, which you can use to perform static analysis:
+
+```
+$ php vendor/bin/phpstan
+```
+
+After making your changes and adding your tests, you can check whether the minimum coverage and minimum mutation score indicator requirements are still met:
+
+```
+$ XDEBUG_MODE=coverage php vendor/bin/phpunit --testsuite unit
+$ php vendor/bin/coverage-check coverage/clover.xml 90
+$ XDEBUG_MODE=coverage php vendor/bin/infection --min-msi=80
+```
+
+## Running test suites
+
+To run all unit tests, use the following command:
+
+```
+$ php vendor/bin/phpunit --testsuite unit --no-coverage
+```
+
+To run all end-to-end tests, use the following command:
+
+```
+$ php vendor/bin/phpunit --testsuite end-to-end --no-coverage
+```