feat(extensions): most of the extensions implementation, by kdb424

docs/porting_to_kmk.md

@@ -0,0 +1,71 @@
+# Porting to KMK 
+Porting a board to KMK is quite simple, and follows this base format.
+
+```python
+import board
+
+from kmk.kmk_keyboard import KMKKeyboard as _KMKKeyboard
+from kmk.matrix import DiodeOrientation
+{EXTENTIONS_IMPORT}
+
+class KMKKeyboard(_KMKKeyboard):
+{REQUIRED}
+    extensions = []
+
+```
+
+## REQUIRED
+This is designed to be replaced with the defining pins of your keyboard. Rows, 
+colums and the diode direction (if any), should be defined like this
+```python
+    row_pins = [board.p0_31, board.p0_29, board.p0_02, board.p1_15]
+    col_pins = [board.p0_22, board.p0_24, board.p1_00, board.p0_11, board.p1_04]
+    diode_orientation = DiodeOrientation.COLUMNS
+```
+
+## Additional pins for extentions
+KMK includes built in extentions for RGB and split keyboards, and powersave. If
+these are applicible on your keyboard/microcontroller, the pins should be added
+here. Refer to the instructions on the respective extentions page on how to add 
+them. If not adding any extentions, leave this as an empty list as shown.
+
+# Coord mapping
+If your keyboard is not built electrically as a square (though most are), you can
+provide a mapping directly. An example of this is the 
+[Corne](https://github.com/foostan/crkbd). That has 12 colums for 3 rows, and 6 
+colums for the bottom row. Split keyboards count as the total keyboard, not per 
+side. That would look like this
+```python
+from kmk.matrix import intify_coordinate as ic
+
+    coord_mapping = []
+    coord_mapping.extend(ic(0, x) for x in range(12))
+    coord_mapping.extend(ic(1, x) for x in range(12))
+    coord_mapping.extend(ic(2, x) for x in range(12))
+    # And now, to handle R3, which at this point is down to just six keys
+    coord_mapping.extend(ic(3, x) for x in range(3, 9))
+```
+
+
+## Keymaps
+Keymaps are organized as a list of lists. Keycodes are added for every key on 
+each layer. See [keycodes](keycodes.md) for more details on what keycodes are 
+avaliable. If using layers or other extentions, also refer to the extentions 
+page for additional keycodes.
+```python
+from kb import KMKKeyboard
+from kmk.keys import KC
+
+keyboard = KMKKeyboard()
+
+keyboard.keymap = [
+    [KC.A, KC.B],
+    [KC.C, KC.D],
+]
+
+if __name__ == '__main__':
+    keyboard.go()
+```
+
+## More information
+More information on keymaps can be found [here](config_and_keymap.md)