Update decode_aprs.h

Co-Authored-By: Vladimir <ew1abz@gmail.com>

Author: ThomasHabets

Diff for: decode_aprs.h

@@ -24,7 +24,7 @@ typedef struct decode_aprs_s {
 
 	int g_quiet;			/* Suppress error messages when decoding. */
 
-	int g_metric;			/* Print metric instead of US customary units */
+	int g_metric;			/* Print metric instead of imperial units */
 
         char g_src[AX25_MAX_ADDR_LEN];
 
@@ -142,4 +142,4 @@ extern void decode_aprs (decode_aprs_t *A, packet_t pp, int quiet, int metric);
 extern void decode_aprs_print (decode_aprs_t *A);
 
 
-#endif
+#endif