changes: document fixed crash on invalid UTF-8 sequences

Document nasm_quote() fixes.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/doc/changes.src b/doc/changes.src
index 4a15ae7..df96ebc 100644
--- a/doc/changes.src
+++ b/doc/changes.src
@@ -37,6 +37,9 @@
 
 \b Support for 64-bit Mach-O output, see \k{machofmt}.
 
+\b Fix assert failure on certain operations that involve high-bit
+  characters that don't form valid UTF-8 sequences.
+
 
 \S{cl-2.06} Version 2.06