Documentation/gpu: Add section for Intel GVT-g host support

Update with brief overview and reference for more detailed
arch design documents.

Add new section for Intel GVT-g host support.

Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

Documentation/gpu/i915.rst

@@ -49,6 +49,15 @@ Intel GVT-g Guest Support(vGPU)
 .. kernel-doc:: drivers/gpu/drm/i915/i915_vgpu.c
    :internal:
 
+Intel GVT-g Host Support(vGPU device model)
+-------------------------------------------
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_gvt.c
+   :doc: Intel GVT-g host support
+
+.. kernel-doc:: drivers/gpu/drm/i915/intel_gvt.c
+   :internal:
+
 Display Hardware Handling
 =========================