Edit FAQ to reference Airflow 2 as a solution to latency problem, closes

 apache#12348 (apache#12450)

docs/faq.rst

@@ -206,7 +206,7 @@ How to reduce airflow dag scheduling latency in production?
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 - ``max_threads``: Scheduler will spawn multiple threads in parallel to schedule dags. This is controlled by ``max_threads`` with default value of 2. User should increase this value to a larger value (e.g numbers of cpus where scheduler runs - 1) in production.
-- ``scheduler_heartbeat_sec``: User should consider to increase ``scheduler_heartbeat_sec`` config to a higher value (e.g 60 secs) which controls how frequent the airflow scheduler gets the heartbeat and updates the job's entry in database.
+- If you're using Airflow 1.10.x, consider moving to Airflow 2, which has reduced dag scheduling latency dramatically, and allows for running multiple schedulers.
 
 Why next_ds or prev_ds might not contain expected values?
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