Getting Started: Take out the links that make the buildbot fail

Author: andypugh

docs/src/getting-started/updating-linuxcnc.adoc

@@ -275,9 +275,7 @@ ton
 
 A framework for controlling ModBus devices using the serial ports on
 many Mesa cards has been introduced.
-http://linuxcnc.org/docs/2.9/html/drivers/mesa_modbus.html
 
 A new GPIO driver for any GPIO which is supported by the gpiod library
 is now included:
-http://linuxcnc.org/docs/2.9/html/drivers/hal_gpio.html