add config sample

custom/conf/app.ini.sample

@@ -385,6 +385,17 @@ CONN_MAX_LIFETIME = 3s
 ; Database maximum number of open connections, default is 0 meaning no maximum
 MAX_OPEN_CONNS = 0
 
+[database_statistic]
+DB_TYPE  = postgres
+HOST     = 127.0.0.1:5432
+NAME     = statistic
+USER     = 
+PASSWD   = 
+SCHEMA   =
+SSL_MODE = disable
+CHARSET  = utf8
+PATH     = 
+
 [indexer]
 ; Issue indexer type, currently support: bleve, db or elasticsearch, default is bleve
 ISSUE_INDEXER_TYPE = bleve