Add forgotten destinations

which is actually the most important for the user

docs/source/man_sbws.ini.rst

 Simple Bandwidth Scanner - SBWS.INI(5)
-=====================================
+======================================
 
 DESCRIPTION
 -----------
@@ -45,9 +45,17 @@ paths
     (Default ~/.sbws/log)
 
 destinations
+  STR = {on, off}
+    Name of destination. It is a name for the Web server from where to
+    download files in order to measure bandwidths.
+
   usability_test_interval = INT
     How often to check if a destination is usable
 
+destinations.STR
+  url = STR
+    The url to the destination
+
 tor
   datadir = STR
     sbws' owned tor directory. (Default: ~/.sbws/tor)