Docs: Vulkan updates for N, arch reorg

Bug: 27621285
Change-Id: Ief97c9247735aaf7bdcedd5e83dd95bd96e2361d
diff --git a/src/devices/graphics/implement.jd b/src/devices/graphics/implement.jd
index 178f4b8..54b4620 100644
--- a/src/devices/graphics/implement.jd
+++ b/src/devices/graphics/implement.jd
@@ -38,6 +38,7 @@
     <li>OpenGL ES 1.x driver</li>
     <li>OpenGL ES 2.0 driver</li>
     <li>OpenGL ES 3.x driver (optional)</li>
+    <li>Vulkan (optional)</li>
     <li>Gralloc HAL implementation</li>
     <li>Hardware Composer HAL implementation</li>
 </ul>
@@ -127,6 +128,16 @@
 <a href="{@docRoot}devices/graphics/implement-vsync.html">Implementing
 VSYNC</a>.</p>
 
+<h3 id=vulkan>Vulkan</h3>
+
+<p>Vulkan is a low-overhead, cross-platform API for high-performance 3D graphics.
+Like OpenGL ES, Vulkan provides tools for creating high-quality, real-time
+graphics in applications. Vulkan advantages include reductions in CPU overhead
+and support for the <a href="https://www.khronos.org/spir">SPIR-V Binary
+Intermediate</a> language. For details on Vulkan, see
+<a href="{@docRoot}devices/graphics/implement-vulkan.html">Implementing
+Vulkan</a>.</p>
+
 <h3 id=virtual_displays>Virtual displays</h3>
 
 <p>Android added platform support for virtual displays in Hardware Composer v1.3.