It very well may be an onion-type hoax, but it sure sounds exactly like what she would say to Africans, doesn’t it?
The folks running the site aren’t fools- it’s a legit site with lots of news etc. I looked carefully and don’t find any indication this is satire. It’s very hard to believe- given the seriousness of what they say she said- that they would make this up.
I just don’t know- but I imagine they’ll be getting emails and phone calls from more than just Michelle Obama very shortly!