Mention transaction id wrap around in xmin warning (#38235)

Author: evantahler

docs/integrations/sources/postgres.md

@@ -192,6 +192,7 @@ This is a good solution if:
 - There is not a well-defined cursor candidate to use for Standard incremental mode.
 - You want to replace a previously configured full-refresh sync.
 - You are replicating Postgres tables less than 500GB.
+- Your database doesn't incur heavy writes that would lead to transaction ID wrap around
 - You are not replicating non-materialized views. Non-materialized views are not supported by xmin replication.
 
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