Prevent on-diff from running for docs changes

Summary: When making changes to docs, target determinator still spawns the on-diff jobs which makes getting changes in take hours. This adds a shipit.strip section to the fboss manifest so that the determinator will ignore changes made in the docs directory.

Reviewed By: shiva-menta

Differential Revision: D81794034

fbshipit-source-id: 1bdb068a665f93f33800044248f161b9e0fcd2d5

Author: KevinYakar

build/fbcode_builder/manifests/fboss

@@ -49,5 +49,8 @@ fbcode/fboss/github = .
 fbcode/fboss/common = common
 fbcode/fboss = fboss
 
+[shipit.strip]
+^fbcode/fboss/github/docs/.*
+
 [sandcastle]
 run_tests = off