Fix missing documentation for many clock faces:

* Move from .c to .h as needed for consistency.
* When missing from both, copy from pull request or wiki.
* When missing entirely, infer functionality from source code.

movement/watch_faces/demo/character_set_face.h

@@ -25,6 +25,17 @@
 #ifndef CHARACTER_SET_FACE_H_
 #define CHARACTER_SET_FACE_H_
 
+/*
+ * CHARACTER SET FACE
+ *
+ * This watch face displays all of the characters in the Sensor Watch character
+ * set. You can advance from one character to the next with a short press of the
+ * ALARM button.
+ *
+ * This watch face may be useful to watch face developers, in that it can help
+ * them to understand which characters will work in different positions.
+ */
+
 #include "movement.h"
 
 void character_set_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr);