Add a known limitation of ORC reader to docs.

Author: marcinsbd

docs/src/main/sphinx/object-storage/file-formats.md

@@ -31,7 +31,8 @@ with ORC files performed by supported object storage connectors:
 [](file-compression) is automatically performed and some details can be
 configured.
 
-Limitations:  
+## ORC support limitations
+
 [Trino ignores Calendar entry in ORC file metadata.](https://github.com/trinodb/trino/issues/26865)
 As a result Trino always treats dates and timestamps as values written using
 proleptic Gregorian calendar. This causes incorrect values read when reading