Minor spelling fix

etc/backup.d/example.dup

@@ -18,7 +18,7 @@ nicelevel = 19
 password = "a_very_complicated_passphrase"
 
 # default is no, for backward compatibility with backupninja <= 0.5.
-# when set to yes, encryptkey option must be set bellow.
+# when set to yes, encryptkey option must be set below.
 sign = yes
 
 # key ID used for data encryption and, optionnally, signing.