config: Add a "printer-" prefix to example printer config files

Add a prefix to the example printer config files so that a sorted
directory listing shows all the samples bundled together.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

config/printer-anycubic-i3-mega-2017.cfg

@@ -0,0 +1,93 @@
+# This file contains pin mappings for the Anycubic i3 Mega with
+# Ultrabase from 2017. (This config may work on an Anycubic i3 Mega v1
+# prior to the Ultrabase if you comment out the definition of the
+# endstop_pin in the stepper_z1 section.) To use this config, the
+# firmware should be compiled for the AVR atmega2560.
+
+# See the example.cfg file for a description of available parameters.
+
+[stepper_x]
+step_pin: ar54
+dir_pin: !ar55
+enable_pin: !ar38
+step_distance: .0125
+endstop_pin: ^!ar3
+position_min: -5
+position_endstop: -5
+position_max: 210
+homing_speed: 30.0
+
+[stepper_y]
+step_pin: ar60
+dir_pin: ar61
+enable_pin: !ar56
+step_distance: .0125
+endstop_pin: ^!ar42
+position_endstop: 0
+position_max: 210
+homing_speed: 30.0
+
+[stepper_z]
+step_pin: ar46
+dir_pin: ar48
+enable_pin: !ar62
+step_distance: .0025
+endstop_pin: ^!ar18
+position_endstop: 0.0
+position_max: 205
+homing_speed: 5.0
+
+[stepper_z1]
+step_pin: ar36
+dir_pin: ar34
+enable_pin: !ar30
+step_distance: .0025
+endstop_pin: ^!ar43
+
+[extruder]
+step_pin: ar26
+dir_pin: ar28
+enable_pin: !ar24
+step_distance: .010799
+nozzle_diameter: 0.400
+filament_diameter: 1.750
+heater_pin: ar10
+sensor_type: ATC Semitec 104GT-2
+sensor_pin: analog13
+control: pid
+pid_Kp: 15.717
+pid_Ki: 0.569
+pid_Kd: 108.451
+min_temp: 0
+max_temp: 245
+
+[heater_fan extruder_fan]
+pin: ar44
+
+[heater_bed]
+heater_pin: ar8
+sensor_type: EPCOS 100K B57560G104F
+sensor_pin: analog14
+control: pid
+pid_Kp: 74.883
+pid_Ki: 1.809
+pid_Kd: 775.038
+min_temp: 0
+max_temp: 110
+
+[fan]
+pin: ar9
+
+[mcu]
+serial: /dev/ttyUSB0
+pin_map: arduino
+
+[printer]
+kinematics: cartesian
+max_velocity: 300
+max_accel: 3000
+max_z_velocity: 10
+max_z_accel: 60
+
+[heater_fan stepstick_fan]
+pin: ar7