Fix small typo (#51542)

Summary:
Fixes https://github.com/pytorch/pytorch/issues/51541

Pull Request resolved: https://github.com/pytorch/pytorch/pull/51542

Reviewed By: albanD

Differential Revision: D26199174

Pulled By: H-Huang

fbshipit-source-id: 919fc4a70d901916eae123672d010e9eb8e8b977
diff --git a/torch/optim/optimizer.py b/torch/optim/optimizer.py
index b3e38c6..53560a5 100644
--- a/torch/optim/optimizer.py
+++ b/torch/optim/optimizer.py
@@ -191,7 +191,7 @@
 
         Args:
             set_to_none (bool): instead of setting to zero, set the grads to None.
-                This is will in general have lower memory footprint, and can modestly improve performance.
+                This will in general have lower memory footprint, and can modestly improve performance.
                 However, it changes certain behaviors. For example:
                 1. When the user tries to access a gradient and perform manual ops on it,
                 a None attribute or a Tensor full of 0s will behave differently.