docs: extract requires a db with regex (#45828)

* docs: extract requires a db with regex

* Update docs/questions/sharing/visualizations/table.md

Co-authored-by: Jeff Bruemmer <jeff.bruemmer@gmail.com>

---------

Co-authored-by: Jeff Bruemmer <jeff.bruemmer@gmail.com>

docs/questions/sharing/visualizations/table.md

@@ -72,6 +72,8 @@ Grab the domain or host from a URL or email. So if you have `https://www.example
 - Domain: `example`
 - Subdomain: `www`
 
+> Extracting domain and host from a URL or email is unavailable for MongoDB, SQLite, and SQL Server. For Druid, extracting domain and host is only available for the Druid-JDBC driver.
+
 ### Sum over time
 
 Add up all the values and group by a time period, generally by month.