usbip: tools: add in man page how to load the client's module

While the man page usbipd.8 already informs the user on which
kernel module has to be used on server side, the man page usbip.8
does not provide any equivalent information on client side.
Also, it could be hard for a newbie to identify the proper usbip
client kernel module, due to the name "vhci-hcd" that has no
immediate assonance with usbip.

Add in usbip.8 the command to add the module vhci-hcd, similarly
as it's already present in usbipd.8 for usbip-host.
While there, rephrase the description of the command "usbip list
--remote=server".
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
--

v1->v2: rephrase the description of command "usbip list ..."
        fix a typo in commit message
Link: https://lore.kernel.org/r/2da8fc9e34440c1fa5f9007baaa3921767cdec50.1593090874.git.borneo.antonio@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/usb/usbip/doc/usbip.8

@@ -83,7 +83,9 @@ List local USB devices.
 .SH EXAMPLES
 
     client:# usbip list --remote=server
-        - List exportable usb devices on the server.
+        - List devices exported by remote server.
+
+    client:# modprobe vhci-hcd
 
     client:# usbip attach --remote=server --busid=1-2
         - Connect the remote USB device.