Documentation: Specify usage of datasource whitelist (#22412)

* Specify usage of datasource whitelist

Added a sentence explaining the data_source_proxy_whitelist  property does not have any effect on pgsql mssql and mysql.

Co-Authored-By: Arve Knudsen <arve.knudsen@gmail.com>
Co-Authored-By: Marcus Efraimsson <marcus.efraimsson@gmail.com>

docs/sources/installation/configuration.md

@@ -350,7 +350,7 @@ Default is `false`.
 
 ### data_source_proxy_whitelist
 
-Define a white list of allowed ips/domains to use in data sources. Format: `ip_or_domain:port` separated by spaces.
+Define a whitelist of allowed IP addresses or domains, with ports, to be used in data source URLs with the Grafana data source proxy. Format: `ip_or_domain:port` separated by spaces. PostgreSQL, MySQL, and MSSQL data sources do not use the proxy and are therefore unaffected by this setting.
 
 ### cookie_secure