Added note about `MAXIDLE` values, set to conservative value of 0xFFFF

firmware/Pre-flight.md

@@ -6,3 +6,9 @@
   - `APRS_ENABLE` is set if APRS is to be used on the flight
   - `APRS_USE_GEOFENCE` is set
   - `DEBUG_USE_INTWATCHDOG` can be disabled during flight. This saves some power
+
+- In `watchdog.h`
+  - Set the various `MAXIDLE` values to values determined during
+    testing. These define how many sleep cycles are permitted in that
+    state before we stop kicking the watchdog. 0xFFFF seems like a
+    good conservative value, but you may want to be more agressive.

firmware/inc/watchdog.h

@@ -42,9 +42,9 @@ typedef enum {
  * Define how many iterations these loops are permitted before a reset
  * is triggered.
  */
-#define MAXIDLE_WAIT_FOR_GPS		0xFFFFFFFE
-#define MAXIDLE_WHILE_TELEMETRY_ACTIVE	0xFFFFFFFE
-#define MAXIDLE_WAIT_FOR_NEXT_TELEMETRY	0xFFFFFFFE
+#define MAXIDLE_WAIT_FOR_GPS		0x0000FFFF
+#define MAXIDLE_WHILE_TELEMETRY_ACTIVE	0x0000FFFF
+#define MAXIDLE_WAIT_FOR_NEXT_TELEMETRY	0x0000FFFF
 
 struct idle_counter {
   uint32_t wait_for_gps;