remove internal rules from .gitignore

Summary: Pull Request resolved: https://github.com/facebookresearch/d2go/pull/198

Differential Revision: D35223296

fbshipit-source-id: 098fc148bc1cea59490cd70ef6f122062b2de7a6

.gitignore

@@ -134,9 +134,5 @@ dmypy.json
 *.DS_Store
 version.py
 
-# internal
-*/**/fb/*
-*/**/*_fb.py
-defs.bzl
-datasets/
+# output dir
 output/