Enabled cannot be updated
Removed the invalid tip that enabled can be updated for existing fields
and clarified instead that it cannot.
Related to and
@@ -92,6 +92,6 @@ GET my_index/_mapping <3>
<2> The document can be retrieved.
<3> Checking the mapping reveals that no fields have been added.
-TIP: The `enabled` setting can be updated on existing fields
-using the <<indices-put-mapping,PUT mapping API>>.
+The `enabled` setting for existing fields and the top-level mapping
+definition cannot be updated.
