Docs: configure grafana database configuration MYSQL (#80939)

* Docs database max_open_conn MYSQL

* Docs: suggestion max_connections

Co-authored-by: Christopher Moyer <35463610+chri2547@users.noreply.github.com>

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Co-authored-by: Christopher Moyer <35463610+chri2547@users.noreply.github.com>

docs/sources/setup-grafana/configure-grafana/_index.md

@@ -369,7 +369,7 @@ The maximum number of connections in the idle connection pool.
 
 ### max_open_conn
 
-The maximum number of open connections to the database.
+The maximum number of open connections to the database. For MYSQL, configure this setting on both Grafana and the database. For more information, refer to [`sysvar_max_connections`](https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_max_connections).
 
 ### conn_max_lifetime