Revert D30359218: [pytorch][PR] [doc] pre-commit fix instructions

Test Plan: revert-hammer

Differential Revision:
D30359218 (pytorch@4e1d84a)

Original commit changeset: 61771babeac4

fbshipit-source-id: c2ac0a4a7463fafa03ad0b20bfb0701a8c1476c4

Author: malfet

CONTRIBUTING.md

@@ -1151,7 +1151,7 @@ formatting and semantic checking of code. We provide a pre-commit git hook for
 performing these checks, before a commit is created:
 
   ```bash
-  ln -s tools/git-pre-commit .git/hooks/pre-commit
+  ln -s ../../tools/git-pre-commit .git/hooks/pre-commit
   ```
 
 You'll need to install an appropriately configured flake8; see