Update const_HALF

src/basic/math_consts/bf11.const_HALF.s

@@ -3,8 +3,13 @@
 ;; #LAYOUT# *   BASIC_0 #TAKE
 ;; #LAYOUT# *   *       #IGNORE
 
+; This file is under the MIT license, it contains code released by Microsoft Corporation.
+; See LICENSE for more information.
+
+; Math package - the constant 1/2
+;
+; This is verified to be identical to the original Microsoft implementation where it was named FHALF
 ;
-; Math package - a constant, for documentation see:
 ; - https://www.c64-wiki.com/wiki/BASIC-ROM
 ; - Computes Mapping the Commodore 64, page 116
 ;