template.c: fix and improve code explanation

src/template.c

@@ -185,12 +185,12 @@ main(void)
 	uint32_t buffer_size = PRODUCT,
 		file_length =
 			4 * 4   /* 4 strings of 4 characters */ +
-			5 * 4   /* 4 uint32_t values */         +
-			4 * 2   /* 5 uint16_t values */         +
+			5 * 4   /* 5 uint32_t values */         +
+			4 * 2   /* 4 uint16_t values */         +
 			PRODUCT /* sample data */
 
 			/* subtract Subchunk2 headers: */
-			- 4 /* a 4-character string */
+			- 4 /* a string of 4 characters */
 			- 4 /* a uint32_t value */,
 		fmt_data_length = 16 /* <--
 		 * length of format data before this value