Short introduction to run the netcore branch

[AlbertoLeon]

I was not able to run the excercise after invest 15min to explore and learn about paket with a few errors not realising that the dependency was in the top of the repository and not in the directory of each lesson solution.

I think that a short introduction in the readme of netcore branch could be helpful.

Maybe you expect some dot net developer to be used to paket, however, it was not my case and I know about other devs that they didn't do also.

I could do a pull request if you think I should do it.

[jamie-lord]

I've just had exactly the same experience