[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/keymaps/default/readme.md

@@ -0,0 +1 @@
+# The default (UK) keymap for pos78