[Beignet] [PATCH] Docs: clarify hardware support, add Neo reference

[Rebecca N. Palmer]

Signed-off-by: Rebecca N. Palmer <rebecca_palmer at zoho.com>

---
Is it a typo that Apollolake is described as 5th (rather than 6th)
generation?  Should the reference to Broxten be removed, as the
hardware was reportedly cancelled?

The Neo supported list is taken from
https://github.com/intel/compute-runtime#supported-platforms

Beignet has supported Coffeelake since 7e181af2 (i.e. never in a stable
release - should that be specified if this is going on the website?).

--- a/docs/Beignet.mdwn
+++ b/docs/Beignet.mdwn
@@ -151,14 +151,23 @@ beignet provides two alternative to run:
 Supported Targets
 -----------------
 
+Beignet is the recommended open source OpenCL driver for these integrated GPUs:
+
  * 3rd Generation Intel Core Processors "Ivybridge".
  * 3rd Generation Intel Atom Processors "BayTrail".
  * 4th Generation Intel Core Processors "Haswell", need kernel patch if your linux kernel older than 4.2, see the "Known Issues" section.
- * 5th Generation Intel Core Processors "Broadwell".
  * 5th Generation Intel Atom Processors "Braswell".
- * 6th Generation Intel Core Processors "Skylake" and "Kabylake".
+
+Beignet also supports these integrated GPUs, but [Intel Compute Runtime (Neo)](https://01.org/compute-runtime) also supports them and offers additional features:
+
+ * 5th Generation Intel Core Processors "Broadwell".
+ * 6th Generation Intel Core Processors "Skylake", "Kabylake" and "Coffeelake".
  * 5th Generation Intel Atom Processors "Broxten" or "Apollolake".
 
+Future GPUs will probably be supported by Intel Compute Runtime only.
+
+Beignet only supports running OpenCL on the integrated GPU, _not_ on the CPU itself (see [pocl](http://portablecl.org) for that).  Systems that also have a discrete GPU may disable the integrated GPU: check _xrandr --listproviders_ or see [here](https://nouveau.freedesktop.org/wiki/Optimus/).
+
 OpenCL 2.0
 ----------
 From release v1.3.0, beignet supports OpenCL 2.0 on Skylake and later hardware.