changes.src: document CLWB and PCOMMIT

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/doc/changes.src b/doc/changes.src
index 3cae1fa..af2abab 100644
--- a/doc/changes.src
+++ b/doc/changes.src
@@ -30,6 +30,11 @@
 
 \b Fix Codeview malformed compiler version record.
 
+\b Add the \c{CLWB} and \c{PCOMMIT} instructions.  Note that the
+   \c{PCOMMIT} instruction has been deprecated and will never be
+   included in a shipping product; it is included for completeness
+   only.
+
 \S{cl-2.12.02} Version 2.12.02
 
 \b Fix preprocessor errors, especially \c{%error} and \c{%warning},