Fix typo

src/config.sample.js

@@ -87,7 +87,7 @@ function (Settings) {
     // Example: "1m", "1h"
     playlist_timespan: "1m",
 
-    // If you want to specify password before saving, please specify it bellow
+    // If you want to specify password before saving, please specify it below
     // The purpose of this password is not security, but to stop some users from accidentally changing dashboards
     admin: {
       password: ''