docs: linuxcnc-uspace-dev rather than linuxcnc-dev in mesa_modbus.adoc

Author: andypugh

docs/src/drivers/mesa_modbus.adoc

@@ -59,7 +59,8 @@ advantage at all.
 
 == Quick Start ==
 
-Install the linuxcnc-dev package.
+Install the linuxcnc-uspace-dev or linuxcnc-dev package (depending on the
+LinuxCNC version installed).
 
 Create a new definition file similar to analogue.mod and relayboard.mod
 (the annotated mesa_uart.mod.sample file should help here)