Docs/fixit: normalize docs for 'page_size' / 'max_results' / 'page_token' (#6842)

Author: tseaver

packages/google-cloud-firestore/google/cloud/firestore_v1beta1/document.py

@@ -459,7 +459,9 @@ def collections(self, page_size=None):
         """List subcollections of the current document.
 
         Args:
-            page_size (Optional[int]]): Iterator page size.
+            page_size (Optional[int]]): The maximum number of collections
+            in each page of results from this request. Non-positive values
+            are ignored. Defaults to a sensible value set by the API.
 
         Returns:
             Sequence[~.firestore_v1beta1.collection.CollectionReference]: