Prioritize CL 3.0 refpages over older sets in search engine results

Per @bashbaug in https://github.com/KhronosGroup/OpenCL-Docs/pull/820#issuecomment-1238775813 . @outofcontrol has set this up for Vulkan specs (see internal gitlab khronos-general/khronos-issues#112) through the webserver and may be able to do this for the CL refpage sets as well. It's also possible to add a rel="canonical" tag into the HTML headers which is something I'd have to setup. For reference, the pages to be prioritized are those under https://registry.khronos.org/OpenCL/sdk/3.0/ vs. those under older versions (1.2, 2.1, etc.)