[Brainstorm] Make advanced kwargs discoverable

[lmazuel]

See #12102 , no-one can guess what kwargs are available just looking at the doc.

We have the content already:
https://github.com/Azure/azure-sdk-for-python/blob/master/sdk/core/azure-core/CLIENT_LIBRARY_DEVELOPER.md#available-policies

How do we make it available for each client? A "aka.ms/options" in all client docstring? Else?

One thing for sure is I don't want to hard-code it, especially since most of these options depends on the version of azure-core, so hard-coding the code makes no sense since the availability will be dependent on the version of installed azure-core, not the installed actual service package.

[xiangyan99]

Now we have https://aka.ms/azsdk/python/options for the advanced kwargs. This always points to the latest core.

We also have https://aka.ms/azsdk/python/options/1.9 for v1.9 core, https://aka.ms/azsdk/python/options/1.8 for v1.8 core, etc.