vulkan: Document codegen instructions and code style

Change-Id: I7565506a866b72f4ce31ac6bdd3d97e357497ab0
(cherry picked from commit e0d27bb1f3671401c2f6d84a60111f5c695c97d3)
diff --git a/vulkan/libvulkan/dispatch.tmpl b/vulkan/libvulkan/dispatch.tmpl
index 0f1194c..054a235 100644
--- a/vulkan/libvulkan/dispatch.tmpl
+++ b/vulkan/libvulkan/dispatch.tmpl
@@ -42,6 +42,8 @@
 •* limitations under the License.
 •*/

+// WARNING: This file is generated. See ../README.md for instructions.

 #define VK_USE_PLATFORM_ANDROID_KHR
 #include <vulkan/vk_android_native_buffer.h>
 #include <vulkan/vk_ext_debug_report.h>
@@ -124,6 +126,8 @@
 •* limitations under the License.
 •*/

+// WARNING: This file is generated. See ../README.md for instructions.

 #include <log/log.h>
 #include <algorithm>
 #include "loader.h"