Content request: Add content that covers Tensor algebra, and differential geometry.

So I had watched all the multivariable/Vector calc videos on Khan. So for me, the next logical step was Tensor stuff, because it is in general relativity and lot of other physics related concepts. Unfortunately, the topic of tensors wasn't in Khan academy. So I am scouring the internet for good explanations, but sadly, there aren't very many. And when there are, you have to have watched videos and read articles from a bunch of different people, about the same thing. Which is really frustrating. So I kindly ask the Khan staff to please consider adding more videos and courses, like Tensor algebra, or differential geometry. Thanks!