Update the Read documentation to show all possible examples

[rhamzeh]

Update the Read Documentation (https://github.com/openfga/api/blob/main/openfga/v1/openfga_service.proto#L29-L138) to mention all possible examples.

See Docs: openfga/openfga.dev#988

And the SDKs: https://github.com/openfga/js-sdk/blob/main/README.md?plain=1#L329-L368