[Keymap] adds pvillano's preonic keymap (#9106)

* adds pvillano's preonic keymap

* Remove unnecessary "\" (tested - ok)

keyboards/preonic/keymaps/pvillano/readme.md

@@ -0,0 +1,25 @@
+# A preonic layout similar to the default,
+
+but with some extra conviences for programming and gaming
+
+## For programming
+
+* Underscore is next to space.
+* Backslash replaces Del on the default layer.
+* Brackets are easy to reach, and are arranged symmetrically.
+
+## For Gaming
+
+* Gaming mode disables OS key.
+* Gaming mode moves ALT to "right space", to be more easily reached.
+* Numpad is available with only the left hand (for emotes).
+
+## Personal taste
+
+* Esc is in the top left, where it belongs
+* Only one Alt layer and one Func layer
+* Function codes are mnemonic
+  * Func + G for Game mode
+  * Func + M for Music mode
+  * Func + N for Num lock
+* No multi-key combos with more than two keys