Add todo note

iot/main/gps.h

@@ -6,6 +6,7 @@
 
 // A lightweight struct to hold location information.
 // TinyGPS++ actually uses a *ton* of RAM so we can't keep the instance around as a global variable
+// FUTURE: Rewrite this to use TinyGPS's integer system instead?
 struct GPSLocation {
 	float lat;
 	float lng;