Missing GPU plugin documentation items

GPU plugin documentation is missing following things:
* Description / table of the resources provided by GPU plugin ('i915', 'i915_monitor', 'tiles'?) and how they work
* Discussion on user / group ID issues for device access, or just link to: https://kubernetes.io/blog/2021/11/09/non-root-containers-and-devices/
* Link to example deployment YAMLs that use GPU resources, e.g. to the `integpu-job.yaml` referred in `README.md` _Testing and Demos_ section: https://github.com/intel/intel-device-plugins-for-kubernetes/blob/main/demo/intelgpu-job.yaml
* Maybe als "Quick start" section, that lists just basics, as current doc is pretty long...