readme and dirs

README.md

@@ -2,5 +2,34 @@
 
 For something in between a grad and a karpathy/micrograd
 
-Requires numpy
+The Tensor class is a wrapper around a numpy array
+
+### Example
+
+```python
+import numpy as np
+from tinygrad.tensor import Tensor
+
+x = Tensor(np.eye(3))
+y = Tensor(np.array([[2.0,0,-2.0]]))
+z = y.dot(x).sum()
+z.backward()
+
+print(x.grad)  # dz/dx
+print(y.grad)  # dz/dy
+```
+
+### Same example in torch
+
+```python
+import torch
+
+x = torch.eye(3, requires_grad=True)
+y = torch.tensor([[2.0,0,-2.0]], requires_grad=True)
+z = y.matmul(x).sum()
+z.backward()
+
+print(x.grad)  # dz/dx
+print(y.grad)  # dz/dy
+```