add mandatory file

CONTRIBUTING.md

+# Contributing to Graphene tutorials
+
+Thanks for your interest in this project.
+
+## Project description
+
+This project contains the graphene container spec and many source code examples of ai-pipelines 
+
+* https://gitlab.eclipse.org/eclipse/graphene/tutorials
+
+## Developer resources
+
+The project maintains the following source code repositories
+
+* https://gitlab.eclipse.org/eclipse/graphene/tutorials
+
+## Eclipse Contributor Agreement
+
+Before your contribution can be accepted by the project team contributors must
+electronically sign the Eclipse Contributor Agreement (ECA).
+
+* http://www.eclipse.org/legal/ECA.php
+
+Commits that are provided by non-committers must have a Signed-off-by field in
+the footer indicating that the author is aware of the terms by which the
+contribution has been provided to the project. The non-committer must
+additionally have an Eclipse Foundation account and must have a signed Eclipse
+Contributor Agreement (ECA) on file.
+
+For more information, please see the Eclipse Committer Handbook:
+https://www.eclipse.org/projects/handbook/#resources-commit
+
+## Contact
+
+Contact the Eclipse Foundation Webdev team via webdev@eclipse-foundation.org.