Add note about support for Airflow < 2.3

Signed-off-by: Kacper Muda <[email protected]>

docs/integrations/airflow/older.md

@@ -27,6 +27,9 @@ This means you don't have to do anything besides configuring where the events ar
 
 ##### Airflow 2.1 - 2.2
 
+> **_NOTE:_** The last version of openlineage-airflow to support Airflow versions below 2.3.0 is 1.14.0  
+  
+
 Integration for those versions has limitations: it does not support tracking failed jobs, 
 and job starts are registered only when a job ends (a `LineageBackend`-based approach collects all metadata 
 for a task on each task's completion).