docs: improve the list of implemented APIs

Suggested-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Eric Engestrom <eric.engestrom@imgtec.com>
diff --git a/docs/intro.html b/docs/intro.html
index d90d0cb..38f40f5 100644
--- a/docs/intro.html
+++ b/docs/intro.html
@@ -27,7 +27,10 @@
 including
 <a href="https://www.khronos.org/opengles/">OpenGL ES</a> (versions 1, 2, 3),
 <a href="https://www.khronos.org/opencl/">OpenCL</a>,
-<a href="https://en.wikipedia.org/wiki/VDPAU">VDPAU</a> and
+<a href="https://www.khronos.org/openmax/">OpenMAX</a>,
+<a href="https://en.wikipedia.org/wiki/VDPAU">VDPAU</a>,
+<a href="https://en.wikipedia.org/wiki/Video_Acceleration_API">VA API</a>,
+<a href="https://en.wikipedia.org/wiki/X-Video_Motion_Compensation">XvMC</a> and
 <a href="https://www.khronos.org/vulkan/">Vulkan</a>.
 </p>