e1000e Kconfig: remove ref to nonexistant docs

There is no Documentation/networking/e1000e.txt.
Signed-off-by: NJason Uhlenkott <jasonuhl@jasonuhl.org>
Cc: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

drivers/net/Kconfig

@@ -1976,9 +1976,6 @@ config E1000E
 
 	  <http://support.intel.com>
 
-	  More specific information on configuring the driver is in
-	  <file:Documentation/networking/e1000e.txt>.
-
 	  To compile this driver as a module, choose M here. The module
 	  will be called e1000e.