describe epp_dir option

configs/by_interface/pico/USC_encod/univstep_load.hal

@@ -12,6 +12,10 @@ loadrt pid num_chan=4
 # install driver
 # if the stepper controller is not connected to the standard parallel port
 # at address 0x378 add port_addr="0x1234" after a space to the following line
+# on LinuxCNC versions 2.7.9 and above, a parameter allows you to change the
+#    way the EPP port is controlled.  For PCIe cards using the NetMos 990x
+#    chips, append epp_dir=1 to the end of the following line
+
 loadrt hal_ppmc
 
 # make some signals for the scope for tuning.