Adding CONTRIBUTION.md

Explaining how people can contribute to this project

Author: DragonBe

CONTRIBUTING.md

@@ -0,0 +1,143 @@
+## Contributing
+
+First off, thank you for considering contributing to HIBP. It's people
+like you that make HIBP such a great tool for anyone who needs to check
+if a given password was previously used in a service that was breached
+and listed in [Have I Been Pwned?](https://haveibeenpwned).
+
+### 1. Where do I go from here?
+
+If you've noticed a bug or have a question, [search the issue tracker](https://github.com/dragonbe/hibp/issues?q=something)
+to see if someone else in the community has already created a ticket.
+If not, go ahead and [make one](https://github.com/dragonbe/hibp/issues/new)!
+
+### 2. Fork the project and create a branch
+
+If this is something you think you can fix, then
+[fork HIBP](https://help.github.com/articles/fork-a-repo)
+and create a branch with a descriptive name.
+
+A good branch name would be (where issue #123 is the ticket you're working on):
+
+```sh
+git checkout -b 123-fixing-nasty-issue
+```
+
+### 3. Get the test suite running
+
+Make sure you're using the most recent PHP version:
+
+- This project uses PHP 7.2 or higher
+
+Now install PHP packages using [composer](https://getcomposer.org):
+
+```sh
+composer install
+```
+
+At this point you should be able to run the entire test suite using:
+
+```sh
+./vendor/bin/phpunit
+```
+
+### 4. Did you find a bug?
+
+* **Ensure the bug was not already reported** by [searching all
+  issues](https://github.com/dragonbe/hibp/issues?q=).
+
+* If you're unable to find an open issue addressing the problem, [open a new
+  one](https://github.com/dragonbe/hibp/issues/new).  Be sure to
+  include a **title and clear description**, as much relevant information as
+  possible, and a **code sample** or an **executable test case** demonstrating
+  the expected behavior that is not occurring.
+
+### 5. Implement your fix or feature
+
+At this point, you're ready to make your changes! Feel free to ask for help;
+everyone is a beginner at first :smile_cat:
+
+### 6. Make a Pull Request
+
+At this point, you should switch back to your master branch and make sure it's
+up to date with HIBP's master branch:
+
+```sh
+git remote add upstream git@github.com:dragonbe/hibp.git
+git checkout master
+git pull upstream master
+```
+
+Then update your feature branch from your local copy of master, and push it!
+
+```sh
+git checkout 123-update-be-vat-numbers
+git rebase master
+git push --set-upstream origin 123-fixing-nasty-issue
+```
+
+Replace `123-fixing-nasty-issue` with the branch name you have given yourself.
+
+Finally, go to GitHub and
+[make a Pull Request](https://help.github.com/articles/creating-a-pull-request)
+:D
+
+Travis CI will run our test suite against all supported PHP versions. We care
+about quality, so your PR won't be merged until all tests pass. It's unlikely,
+but it's possible that your changes pass tests in one PHP version but fails in
+another. In that case, you'll have to setup your development environment (as
+explained in step 3) to use the problematic PHP version, and investigate
+what's going on!
+
+The [PHP containers on Docker HUB](https://hub.docker.com/_/php) might be 
+convenient for this purpose. You might want to make use of them.
+
+### 7. Keeping your Pull Request updated
+
+If a maintainer asks you to "rebase" your PR, they're saying that a lot of code
+has changed, and that you need to update your branch so it's easier to merge.
+
+To learn more about rebasing in Git, there are a lot of
+[good](http://git-scm.com/book/en/Git-Branching-Rebasing)
+[resources](https://help.github.com/articles/interactive-rebase),
+but here's the suggested workflow:
+
+```sh
+git checkout 123-fixing-nasty-issue
+git pull --rebase upstream master
+git push --force-with-lease 123-fixing-nasty-issue
+```
+
+### 8. Merging a PR (maintainers only)
+
+A PR can only be merged into master by a maintainer if:
+
+* It is passing CI.
+* It has been approved by at least two maintainers. If it was a maintainer who
+  opened the PR, only one extra approval is needed.
+* It has no requested changes.
+* It is up to date with current master.
+
+Any maintainer is allowed to merge a PR if all of these conditions are
+met.
+
+### 9. Shipping a release (maintainers only)
+
+Maintainers need to do the following to push out a release:
+
+* Make sure all pull requests are in
+* Create a stable branch for that release:
+
+This example explains the process to tag a new version on `master`, where
+`upstream` references [dragonbe/hibp](https://github.com/dragonbe/hibp)and 2.0.8 
+is our latest tag.
+
+  ```sh
+  git fetch upstream
+  git checkout master
+  git pull --rebase upstream master
+  git tag -a 2.0.9
+  git push upstream 2.0.9 
+  ```
+
+That's all there is to it.