fsSize() added optional drive parameter

docs/filesystem.html

@@ -663,14 +663,14 @@ setInterval(function() {
                   </thead>
                   <tbody>
                     <tr>
-                      <td>si.fsSize(cb)</td>
+                      <td>si.fsSize(drive, cb)</td>
                       <td>[{...}]</td>
                       <td>X</td>
                       <td>X</td>
                       <td>X</td>
                       <td>X</td>
                       <td></td>
-                      <td>returns array of mounted file systems</td>
+                      <td>returns array of mounted file systems<br>drive parameter is optional</td>
                     </tr>
                     <tr>
                       <td></td>
@@ -1011,4 +1011,4 @@ setInterval(function() {
   </script>
 </body>
 
-</html>
+</html>