DOC: parallel safe (#24638)

Author: TomAugspurger

doc/sphinxext/contributors.py

@@ -46,4 +46,8 @@ def run(self):
 def setup(app):
     app.add_directive('contributors', ContributorsDirective)
 
-    return {'version': '0.1'}
+    return {
+        'version': '0.1',
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+    }