A written walkthrough for contribution to the Neos Flow Framework

Right now I will like to get my code setup going - I’ve ben wanting to introduce a AccontInterface for a while, but I haven’t been able to.

If we should talk about docs, I will be more than happy to move the whole Documentation folder of the Neos.Flow package into docs.neos.io/flow so it gets its own namespace - and then write the chapter.

But one thing at a time