[Keymap] Gherkin SuperMicro 28 (#8886)

* Gherkin SuperMicro 28

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/keymap.c

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/keymap.c

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/keymap.c

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/config.h

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/rules.mk

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/rules.mk

* removed jpegs

* removed jpegs

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/keymap.c

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/rules.mk

* removed firmware sizes

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/keymap.c

* Update keyboards/40percentclub/gherkin/keymaps/stevexyz/rules.mk

* Update keymap.c

keyboards/40percentclub/gherkin/keymaps/stevexyz/readme.md

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+# gherkin super micro edition
+
+With this configuration the "28" layout first experimented on the plank-like jj40 is being ported to a more proper board, leaving just two keys not used.
+
+For more information please have a look at https://github.com/stevexyz/qmk_firmware/blob/master/keyboards/jj40/keymaps/stevexyz/readme.md 
+
+The image below explain the main layers. In addition to them with q, w and e there are three specific dedicated layers for cursors/mouse, numpad and media.
+![layers](https://raw.githubusercontent.com/stevexyz/qmk_firmware/master/keyboards/40percentclub/gherkin/keymaps/stevexyz/layers.jpeg)
+
+![prototype](https://github.com/stevexyz/qmk_firmware/blob/master/keyboards/40percentclub/gherkin/keymaps/stevexyz/gherkin28.jpeg)
+
+Happy hacking!
+_Stefano