[doc] add argument default values in rot90 (pytorch#85610)

Add argument default values in rot90.
Pull Request resolved: pytorch#85610
Approved by: https://github.com/lezcano

torch/_torch_docs.py

@@ -11274,15 +11274,15 @@ def merge_dicts(*dicts):
 add_docstr(
     torch.rot90,
     r"""
-rot90(input, k, dims) -> Tensor
+rot90(input, k=1, dims=[0,1]) -> Tensor
 
 Rotate a n-D tensor by 90 degrees in the plane specified by dims axis.
 Rotation direction is from the first towards the second axis if k > 0, and from the second towards the first for k < 0.
 
 Args:
     {input}
-    k (int): number of times to rotate
-    dims (a list or tuple): axis to rotate
+    k (int): number of times to rotate. Default value is 1
+    dims (a list or tuple): axis to rotate. Default value is [0, 1]
 
 Example::