Merge pull request #174 from mollie/docs/release-info

docs: add release procedure info to contribution guidelines

docs/ContributionGuidelines.md

@@ -26,4 +26,15 @@ While developing project you can use some predefined commands for running tests,
 - Execute `npm run test:coverage` to run all tests and print the code coverage report.
 - Execute `npm run test:unit` to run Unit tests.
 - Execute `npm run test:component` to run Component tests.
-- Execute `npm run lint` to show lint errors in the code.
+- Execute `npm run lint` to show lint errors in the code.
+
+## Release procedure
+At the moment there is no automated release scripts, which means we do releases manually. We use [gitflow workflow](https://www.atlassian.com/git/tutorials/comparing-workflows/gitflow-workflow) for releases. Please **squash commits when finishing the feature branch**, this way we can keep relatively clean history on develop and main. 
+
+Release following these steps:
+
+1. Create and check out release branch off develop once new features are ready to be released (`release/<tag>`).
+2. Bump [version](https://semver.org/) on npm packages (both extension and notifications). Commit changes on release branch.
+3. Create PR and merge release branch to main. Do not squash commits at this stage.
+4. Create a new tag on main and create release on [GitHub](https://github.com/mollie/commercetools/releases).
+5. Create PR and merge main branch back to develop. Do not squash commits at this stage.