Documentation: example URL gives 404

[hoegrammer]

In the README there is an example command:

prism mock https://raw.githack.com/OAI/OpenAPI-Specification/master/examples/v3.0/petstore-expanded.yaml

This does not work because https://raw.githack.com/OAI/OpenAPI-Specification/master/examples/v3.0/petstore-expanded.yaml returns a 404

Context

Improve documentation

Current Behavior

Expected Behavior

Possible Solution(s)