doc/changes.src: add missing blank line between bullet points

Bullet points are considered paragraphs, so our documentation compiler
require an empty line between them.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/doc/changes.src b/doc/changes.src
index aad02a7..e72457c 100644
--- a/doc/changes.src
+++ b/doc/changes.src
@@ -10,6 +10,7 @@
 \S{cl-2.13.03} Version 2.13.03
 
 \b Added AVX and AVX512 \c{VAES*} and \c{VPCLMULQDQ} instructions.
+
 \b Fixed missing dwarf record in x32 ELF output format.
 
 \S{cl-2.13.02} Version 2.13.02