feat(behaviors): Add caps word (&caps_word).

* Add new `&caps_word` behavior that acts like caps lock, but
  releases automatically when any "break" keycode is pressed.

app/dts/bindings/behaviors/zmk,behavior-caps-word.yaml

@@ -0,0 +1,15 @@
+# Copyright (c) 2021 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Caps word behavior
+
+compatible: "zmk,behavior-caps-word"
+
+include: zero_param.yaml
+
+properties:
+  continue-list:
+    type: array
+    required: true
+  mods:
+    type: int