runtime(doc): Update change.txt (#13725)

Fix-up and clarify commit  e06f2b4

Signed-off-by: Ken Takata <kentkt@csc.jp>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/change.txt

@@ -1,4 +1,4 @@
-*change.txt*    For Vim version 9.0.  Last change: 2023 Dec 08
+*change.txt*    For Vim version 9.0.  Last change: 2023 Dec 19
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -452,9 +452,12 @@ octal number.
 Note that when 'nrformats' includes "octal", decimal numbers with leading
 zeros cause mistakes, because they can be confused with octal numbers.
 
-Note similarly, when 'nrformats' includes "bin", binary numbers with a leading
-'0b' or '0B' can be interpreted as hexadecimal rather than binary since '0b'
-are valid hexadecimal digits.
+Note similarly, when 'nrformats' includes both "bin" and "hex", binary numbers
+with a leading '0x' or '0X' can be interpreted as hexadecimal rather than
+binary since '0b' are valid hexadecimal digits.  CTRL-A on "0x0b11" results in
+"0x0b12", not "0x0b100".
+When 'nrformats' includes "bin" and doesn't include "hex", CTRL-A on "0b11" in
+"0x0b11" results in "0x0b100".
 
 When the number under the cursor is too big to fit into 32 or 64 bit
 (depending on how Vim was build), it will be rounded off to the nearest number