Add state of project to README

[deflomu]

From just looking at this project for a few minutes it is unclear to me what the actual state of this project is. There are some bugs that say: "foo() is not functional". Could you add a section to the readme that tells new users what they can expect from this? Maybe some compatibility informations and what's planed in the near future or something. Also it is not clear to me if this is a well supported project from microsoft or if I should expect it to be not continued any time soon because the main developer focuses on other things or in other words how official this is.