docs: create_users_csv docstring

Author: jorwoods

Diff for: tableauserverclient/server/endpoint/users_endpoint.py

@@ -257,9 +257,19 @@ def filter(self, *invalid, page_size: Optional[int] = None, **kwargs) -> QuerySe
 
         return super().filter(*invalid, page_size=page_size, **kwargs)
 
+
 def create_users_csv(users: Iterable[UserItem], identity_pool=None) -> bytes:
     """
-    Create a CSV byte string from an Iterable of UserItem objects
+    Create a CSV byte string from an Iterable of UserItem objects. The CSV will
+    have the following columns, and no header row:
+
+    - Username
+    - Password
+    - Display Name
+    - License
+    - Admin Level
+    - Publish capability
+    - Email
     """
     if identity_pool is not None:
         raise NotImplementedError("Identity pool is not supported in this version")