Adding jj40 to keyboard list (#2315)

* Adding jj40 to keyboard list

Adding jj40 to Community-supported list.

* Update readme.md

keyboards/readme.md

@@ -44,6 +44,7 @@ These keyboards are part of the QMK repository, but their manufacturers are not
 * [Happy Hacking Keyboard](/keyboards/hhkb) — The Happy Hacking keyboard can be hacked with a custom controller to run QMK.
 * [Infinity 60%](/keyboards/infinity60) - — Compact community keyboard by Input Club.
 * [JD45](/keyboards/jd45) — Another Geekhack community project, designed by jdcarpe.
+* [JJ40](/keyboards/jj40) — ps2avrGB based ortholinear sold by KPrepublic
 * [KBD75](/keyboards/kbd75) — A 75% keyboard made by made by KBDFans.
 * [KC60](/keyboards/kc60) — A programmable Chinese-made keyboard, lost in the mists of time.
 * [Kinesis Advantage](/keyboards/kinesis) — Contoured ergonomic keyboard by Kinesis Computer Ergonomics.