Configuration: Improve session_lifetime comments (#16238)

conf/defaults.ini

@@ -141,7 +141,7 @@ cookie_name = grafana_sess
 # If you use session in https only, default is false
 cookie_secure = false
 
-# Session life time, default is 86400
+# Session life time, default is 86400 (means 86400 seconds or 24 hours)
 session_life_time = 86400
 gc_interval_time = 86400
 

conf/sample.ini

@@ -132,7 +132,7 @@ log_queries =
 # If you use session in https only, default is false
 ;cookie_secure = false
 
-# Session life time, default is 86400
+# Session life time, default is 86400 (means 86400 seconds or 24 hours)
 ;session_life_time = 86400
 
 #################################### Data proxy ###########################