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/complication/moon_phase_face.h

@@ -25,6 +25,30 @@
 #ifndef MOON_PHASE_FACE_H_
 #define MOON_PHASE_FACE_H_
 
+/*
+ * MOON PHASE face
+ *
+ * The Moon Phase face is similar to the Sunrise/Sunset face: it displays the
+ * current phase of the moon, along with the day of the month and a graphical
+ * representation of the moon on the top row.
+ * 
+ * This graphical representation is a bit abstract. The segments that turn on
+ * represent the shape of the moon, waxing from the bottom right and waning at
+ * the top left. A small crescent at the bottom right will grow into a larger
+ * crescent, then add lines in the center for a quarter and half moon. All
+ * segments are on during a full moon. Then gradually the segments at the
+ * bottom right will turn off, until all that remains is a small waning
+ * crescent at the top left.
+ * 
+ * All segments turn off during a new moon.
+ * 
+ * On this screen you may press the Alarm button repeatedly to move forward
+ * in time: the day of the month at the top right will advance by one day for
+ * each button press, and both the text and the graphical representation will
+ * display the moon phase for that day. Try pressing the Alarm button 27 times
+ * now, just to visualize what the moon will look like over the next month.
+ */
+
 #include "movement.h"
 
 typedef struct {