implements oneshot/sticky keys.

docs/modules.md

@@ -11,6 +11,7 @@ modules are
 put on your keyboard
 - [ModTap](modtap.md): Adds support for augmented modifier keys to act as one key
 when tapped, and modifier when held.
+- [OneShot](oneshot.md): Adds support for oneshot/sticky keys.
 - [Power](power.md): Power saving features. This is mostly useful when on battery power.
 - [Split](split_keyboards.md): Keyboards split in two. Seems ergonomic!
 - [TapDance](tapdance.md): Different key actions depending on how often it is pressed.

docs/oneshot.md

@@ -0,0 +1,32 @@
+# OneShot Keycodes
+OneShot keys or sticky keys enable you to have keys that keep staying pressed
+for a certain time or until another key is pressed and released.
+If the timeout expires or other keys are pressed, and the sticky key wasn't
+released, it is handled as a regular key hold.
+
+## Enable OneShot Keys
+
+```python
+from kmk.modules.oneshot import OneShot
+oneshot = OneShot()
+# optional: set a custom tap timeout in ms (default: 1000ms)
+# oneshot.tap_time = 1500
+keyboard.modules.append(modtap)
+```
+
+## Keycodes
+
+|Keycode          | Aliases      |Description                       |
+|`KC.OS(KC.ANY)`  | `KC.ONESHOT` |make a sticky version of `KC.ANY` |
+
+`KC.ONESHOT` accepts any valid key code as argument, including modifiers and KMK
+internal keys like momentary layer shifts.
+
+## Custom OneShot Behavior
+The full OneShot signature is as follows:
+```python
+KC.OS(
+    KC.TAP, # the sticky keycode
+    tap_time=None # length of the tap timeout in milliseconds
+    )
+```