Narrow Apron LED user mod

[rrz-dev]

I made a mod to use the apron leds on a v1.1 (upgrade) with narrow thumper blocks without loosing a gate.

[moggieuk]

Not speaking for the whole team, but I'm ok with this as a contributed mod but understand that it isn't a ERCFv2 anymore. I'd like to make that clear so it doesn't cause problems with Happy Hare vendor "ERCF, version "2.0". With 21mm blocks this would be a "Custom" vendor and need to set correctly:

# ADVANCED/CUSTOM MMU: See documentation for use of these ----------------------------------------------------------------
#
# Normally all these settings are set based on your choice of 'mmu_vendor' and 'mmu_version', but they can be overridden.
# If you have selected a vendor of "Other" you must set these else you will get arbitary ERCFv1.1 defaults.
#
#cad_gate0_pos: 4.2			# Approximate distance from endstop to first gate. Used for rough calibration only
#cad_gate_width: 21.0			# Width of each gate
#cad_bypass_offset: 0			# Distance from limit of travel back to the bypass (ERCF v2.0)
#cad_last_gate_offset: 2.0		# Distance from limit of travel back to last gate
#cad_selector_tolerance: 10.0 		# How much extra selector movement to allow
#
#encoder_default_resolution: 0.676	# Approximate resolution(mm) of a single encoder "count". Not used for measurement

It would be good for the PR to include all the necessary settings for HH..

[rrz-dev]

Ok, very good suggestions and remarks. I will add the settings to the PR.