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/settings/set_time_hackwatch_face.h

@@ -25,6 +25,29 @@
 #ifndef SET_TIME_HACKWATCH_FACE_H_
 #define SET_TIME_HACKWATCH_FACE_H_
 
+/*
+ * SET TIME HACKWATCH
+ *
+ * This is an extended version of set_time face which allow setting seconds
+ * precisely. To achieve that - press and hold alarm button few seconds before
+ * 00 and release exaclty as reference clock turns 00.
+ *
+ * All settings can go up, or down (long alarm press).
+ * 
+ * The challenge is that SensorWatch display is delayed 0.5 seconds vs hardware
+ * RTC clock. It is caused by interrupts being generated by raising edge of
+ * counter. It means there is no way to precisely trigger at 0.5s, as events
+ * at different frequencies slightly mismatch. This watch face achieves this
+ * approximately by triggering at 15th out of 32Hz events.
+ * 
+ * If you are <30 seconds when setting seconds - you will stay in the same
+ * minute. Otherwise - you will go to next minute. 
+ * 
+ * Note that changing anything will slightly delay subseconds counter. This
+ * is why this face sets seconds last to achiveve best precision. Still,
+ * best possible precision is achieved with finetune face. 
+ */
+
 #include "movement.h"
 
 void set_time_hackwatch_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr);