DataPlaneFramework: add documentation

[paullatzelsperger]

For the DPF we should have the following developer documentation items showing how to

• set up a DPF runtime
• configure an EDC so that it can communicate with the DPF
• develop your first DataSource and DataSink

In addition, creating Youtube videos will greatly aid understanding.

[MoritzKeppler]

Would be great also to have documentation for which scenarios the dataplane framework is a suitable solution, so especially document limitations.

[jimmarino]

Closing this as some items have been done and others are wish list items.