[Keyboard] Add POS78 keyboard (#11024)

* Add pos78 keyboard

* tidy up links

* Added missing commas

The missing commas were causing a compile error (Travis CI, #41934 failed).

* Added trailing commas 

On lines 10-14, just missed last line (15).

* Travis CI errors

Trying to correct errors from Travis CI #41951 failed

* Corrected(?) TG(_FN) from Travis CI failure

* Revert readme.md to original format

Fauxpark

Co-authored-by: Ryan <fauxpark@gmail.com>

* Remove trailing \ from keymap.c

Fauxpark

Co-authored-by: Ryan <fauxpark@gmail.com>

* Change Vendor and Product ID

How do I update the Product ID search tool if 0x7878 is used/good?

* Add  LAYOUT_ortho_6x13 Update keyboards/pos78/pos78.h

Co-authored-by: Drashna Jaelre <drashna@live.com>

* I bow to drashna's superior knowledge. Update keyboards/pos78/info.json

Co-authored-by: Drashna Jaelre <drashna@live.com>

* I bow to drashna's superior knowledge.  Update keyboards/pos78/keymaps/default/keymap.c

Co-authored-by: Drashna Jaelre <drashna@live.com>

* I bow to drashna's superior knowledge.   Update keyboards/pos78/keymaps/default/keymap.c

Co-authored-by: Drashna Jaelre <drashna@live.com>

* Added pic

* Add picture properly. Update keyboards/pos78/readme.md

Co-authored-by: Ryan <fauxpark@gmail.com>

* Remove Bootmagic_enable (fauxpark)

Co-authored-by: Ryan <fauxpark@gmail.com>

Co-authored-by: Ryan <fauxpark@gmail.com>
Co-authored-by: Drashna Jaelre <drashna@live.com>

keyboards/pos78/rules.mk

@@ -0,0 +1,22 @@
+# MCU name
+MCU = atmega32u4
+
+# Bootloader selection
+BOOTLOADER = atmel-dfu
+
+# Build Options
+#   change yes to no to disable
+#
+BOOTMAGIC_ENABLE = lite     # Virtual DIP switch configuration
+MOUSEKEY_ENABLE = yes       # Mouse keys
+EXTRAKEY_ENABLE = yes       # Audio control and System control
+CONSOLE_ENABLE = no         # Console for debug
+COMMAND_ENABLE = no         # Commands for debug and configuration
+# Do not enable SLEEP_LED_ENABLE. it uses the same timer as BACKLIGHT_ENABLE
+SLEEP_LED_ENABLE = no       # Breathing sleep LED during USB suspend
+# if this doesn't work, see here: https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-work
+NKRO_ENABLE = no            # USB Nkey Rollover
+BACKLIGHT_ENABLE = no       # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = no        # Enable keyboard RGB underglow
+BLUETOOTH_ENABLE = no       # Enable Bluetooth
+AUDIO_ENABLE = no           # Audio output