Add Intel IWMMXT2 link, patch by Dmitry Antipov, dmantipov yandex ru.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@13467 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

doc/optimization.txt

@@ -200,6 +200,8 @@ Optimization guide for ARM11 (used in Nokia N800 Internet Tablet):
 http://infocenter.arm.com/help/topic/com.arm.doc.ddi0211j/DDI0211J_arm1136_r1p5_trm.pdf
 Optimization guide for Intel XScale (used in Sharp Zaurus PDA):
 http://download.intel.com/design/intelxscale/27347302.pdf
+Intel Wireless MMX2 Coprocessor: Programmers Reference Manual
+http://download.intel.com/design/intelxscale/31451001.pdf
 
 PowerPC-specific:
 -----------------