conf: adds sample values for db conn settings

conf/sample.ini

@@ -82,6 +82,12 @@
 # For "sqlite3" only, path relative to data_path setting
 ;path = grafana.db
 
+# Max conn setting default is 0 (mean not set)
+;max_conn =
+;max_idle_conn =
+;max_open_conn =
+
+
 #################################### Session ####################################
 [session]
 # Either "memory", "file", "redis", "mysql", "postgres", default is "file"