vk: Add README

Requested by developers outside Intel.

During the driver's pre-release development, let's make the README easy
to find for external experimenters. Keep it at the top of the source
tree.

README.intel-vulkan.txt

@@ -0,0 +1,128 @@
+Intel's Open Source Vulkan Driver
+Vulkan API Version: 0.170.2
+
+Intro
+=====
+The Open Source Technology Center 3D graphics team at Intel has
+been working on a Vulkan implementation based on the Mesa open source
+OpenGL implementation. At this point we're ready to share what we have
+with our Khronos friends, in the hope that an early preview will be
+useful.
+
+When the Vulkan specification goes public, we will continue the work
+in the Mesa public git repository, but in the interim we will share
+our progress on the 'vulkan' branch in the 'mesa' repository in
+Khronos gitlab.
+
+The Mesa project source and our driver implementation is under the MIT
+license [1], but is also covered by the Khronos IP framework as it
+pertains to a specification under construction [2].
+
+We welcome all feedback and contibutions, as long as the contributions
+are MIT licensed and can be open sourced with the driver.
+
+[1] https://opensource.org/licenses/MIT
+[2] https://www.khronos.org/members/ip-framework
+
+
+Maintainers
+===========
+Kristian Høgsberg Kristensen <kristian.h.kristensen@intel.com>
+Jason Ekstrand <jason.ekstrand@intel.com>
+Chad Versace <chad.versace@intel.com>
+
+
+Supported Hardware
+==================
+- Broadwell, main development focus
+- Ivybridge, early experimental support
+
+
+Supported OS Platforms
+======================
+ - Linux, tested on Fedora 22 with kernel >= 4.1
+     - X11 with DRI3
+     - Wayland
+ - Android
+     - TODO
+
+
+Building and Installing
+=======================
+This driver is intended to be used directly from the build tree. Installing the
+driver into a system location is not yet fully supported. If you require support
+for system-wide installation, please contact a maintainer.
+
+Throughout the instructions, MESA_TOP refers to the top of the Mesa repository.
+
+First, install the usual dependencies needed to build Mesa.
+
+        Fedora:
+            $ sudo yum builddep mesa
+        Ubunutu:
+            $ FINISHME
+
+Next, configure and build. The below commands will build Mesa in release mode.
+If you wish to build Mesa in debug mode, add option '--enable-debug' to the
+configure command.
+
+        $ cd $MESA_TOP
+        $ autoreconf -vfi
+        $ ./configure --with-dri-drivers=i965 --with-gallium-drivers=
+        $ make
+
+To use the driver's libvulkan.so directly, without LunarG's loader, you must set
+an environment variable before running your Vulkan application:
+
+        $ export LD_LIBRARY_PATH="$MESA_TOP/lib"
+        $ your-vk-app
+
+Alternatively, to use the driver with LunarG's loader:
+
+        $ export VK_ICD_FILENAMES="$MESA_TOP/src/vulkan/anv_icd.json"
+        $ your-vk-app
+
+
+File Structure and Naming
+=========================
+The core code of Intel's Mesa Vulkan driver lives in src/vulkan. Files prefixed
+with "gen8" support Broadwell; files prefixed with "gen7" support Ivybridge;
+files prefixed with "anv" are common to all hardware generations.
+
+Mesa is an umbrella open source project containing many drivers for multiple
+APIs. The codename for Intel's Mesa Vulkan driver is "Anvil", hence the filename
+prefix "anv".
+
+
+Feature Status
+==============
+The driver is still a work-in-progress. We do our best to keep the below list of
+features up-to-date.
+
+Supported Features:
+  - Index buffers, instanced draw, indirect draw
+  - Nested command buffers
+  - Consumes SPIR-V (no GLSL "backdoor")
+  - Fragment and vertex shaders
+  - Uniform buffers, sampled images, dynamic uniform buffers
+  - Push constants (to the extent they're supported by SPIR-V v32)
+  - Color, depth and stencil attachments
+  - 1D, 2D, 3D textures, texture arrays
+  - Memory barrier
+  - Optionally integrates with LunarGs loader
+  - WSI extension for X11
+  - Fences
+  - Most copy/blit commands for color and depth buffers,
+    vkCmdCopyImageToBuffer for stencil buffers
+  - Occlution query and timestamps
+
+Unsupported Features:
+   - Shader storage buffers
+   - Shader specialization
+   - Storage images
+   - Compute, tesselation, geometry stages
+   - Sparse resources
+   - MSAA
+   - VkkSemaphore and VkEvent
+   - vkCmdClear commands
+   - Input attachments