* remove the openwebui in inference-cpp-xpu dockerfile
* update docker_cpp_xpu_quickstart.md
* add sample output in inference-cpp/readme
* remove the openwebui in main readme
* remove the openwebui in main readme
* transfer files in DockerGuides from rst to md
* add some dividing lines
* adjust the title hierarchy in docker_cpp_xpu_quickstart.md
* restore
* switch to the correct branch
* small change
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Co-authored-by: ATMxsp01 <shou.xu@intel.com>