Switch to GitHub Flow development workflow (#141)

git flow is a bit too heavy and this way we align ourselves to our Helm charts development workflow.

CONTRIBUTING.md

@@ -2,18 +2,24 @@
 
 This repository contains FADI documentation (usage, installation, ...).
 
+We are using the [GitHub Flow](https://githubflow.github.io/) development workflow.
+
 ## Submitting changes
 
 Please send a Pull Request with a clear description of what you have done (read more about [pull requests](https://help.github.com/en/articles/about-pull-requests)).
 
 ## Reviewing changes
 
-* make sure the PR is made on the `develop` branch
-* in case some additional work is needed on a external fork pull request, see https://gist.github.com/Chaser324/ce0505fbed06b947d962
+* in case some additional work is needed on a external fork pull request, see [how to manage pull requests and merging](https://gist.github.com/Chaser324/ce0505fbed06b947d962)
+
+## Releasing
+
+* version tag should be aligned to the [FADI Helm chart version](https://github.com/cetic/helm-fadi/releases)
+* release notes can be [automatically generated](https://docs.github.com/en/repositories/releasing-projects-on-github/automatically-generated-release-notes) from pull requests
 
 ## Tools
 
 * Screen casts were made using https://nimbusweb.me/screenshot.php and converted to .gif using https://cloudconvert.com/mp4-to-gif
-* Carousel was done with https://ezgif.com/maker
-* Architecture diagrams are made with https://draw.io
+* Architecture diagrams are made with https://app.diagrams.net/
+* README.md carousel was done with https://ezgif.com/maker
 * Icons are CC0 and mostly from https://svgsilh.com