Add README.md

README.md

+The project My-Aktion implements a REST API with Spring Boot for
+managing donation campaigns.
+The repository contains a step-by-step implementation following
+the respective exercise in the hands-on training booklet of lecture
+**Distributed Systems**. You'll find the use cases and the domain model in the booklet, too.
+
+Each part of the exercise is realized in a separate branch.
+The branches were built on each other (technically speaking: they were rebased on their respective predecessor)
+in the following order:
+
+* start
+* service-data
+* logging
+* rest-api
+* validation
+* advices
+* extra-mile
+
+You can checkout the branches to see the state of development for the corresponding part of the exercise
+by `git checkout <branch_name>.` or by using the GitLab UI.
+
+This `README.md` file may contain specific informations about the current branch.