add reference to flake8-mypy in contributing.md

Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/17759

Differential Revision: D14376813

Pulled By: eellison

fbshipit-source-id: cca1128e967ef7368633b94a3fa3c8e76a4a16f4

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 3a29518..1329b04 100644 (file)
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -335,7 +335,7 @@ Hope this helps, and thanks for considering to contribute.
 
 ## Windows development tips
 
-For building from source on Windows, consult 
+For building from source on Windows, consult
 [our documentation](https://pytorch.org/docs/stable/notes/windows.html) on it.
 
 Occasionally, you will write a patch which works on Linux, but fails CI on Windows.
@@ -475,11 +475,12 @@ which is in PyTorch's `requirements.txt`.
 
 ### Pre-commit Tidy/Linting Hook
 
-We use clang-tidy and flake8 to perform additional formatting and semantic checking
-of code. We provide a pre-commit git hook for performing these checks, before
-a commit is created:
+We use clang-tidy and flake8 (installed with flake-mypy) to perform additional
+formatting and semantic checking of code. We provide a pre-commit git hook for
+performing these checks, before a commit is created:
 
   ```bash
+  pip install flake8-mypy
   ln -s ../../tools/git-pre-commit .git/hooks/pre-commit
   ```