implement keyboard lock status reader API

docs/lock_status.md

@@ -0,0 +1,23 @@
+# Lock Status
+This extension exposes host-side locks like caps or num lock.
+
+## Enabling the extension
+```python
+from kmk.extensions.lock_status import LockStatus
+
+locks = LockStatus()
+keyboard.extensions.append(locks)
+
+```
+
+## Read Lock Status
+Lock states can be retrieved with getter methods and are truth valued -- `True`
+when the lock is enabled and `False` otherwise.
+
+|Method                    |Description |
+|--------------------------|------------|
+|`locks.get_caps_lock() `  |Num Lock    |
+|`locks.get_caps_lock() `  |Caps Lock   |
+|`locks.get_scroll_lock() `|Scroll Lock |
+|`locks.get_compose() `    |Compose     |
+|`locks.get_kana() `       |Kana        |