[GSD-11616] Create the documentation for environment variables

Hi,
It was found that if I want to find some definition for environment variables from [the list](https://github.com/intel/compute-runtime/blob/master/shared/source/debug_settings/debug_variables_base.inl), I need to go over the list and try to not break eyes looking at the list and try to guess what is the real definition is :)

Could you please create any human-friendly documentation (.md, github pages or something else) that can contain clear definitions for variables?
Example:
instead of `DECLARE_DEBUG_VARIABLE(int32_t, RenderCompressedBuffersEnabled, -1, "-1: default, 0: disabled, 1: enabled")`
let's have
| RenderCompressedBuffersEnabled | what it does, how the behavior is changed | -1 (default value) | possible values with meaning |