Doc formatting issues on getting started

[artberger]

The doc page for the getting started has some formatting errors such as ordered steps and raw codeblocks: https://gateway-api-inference-extension.sigs.k8s.io/guides/

There are also some outdated references to the old k8sgateway project name that can be updated to kgateway: https://gateway-api-inference-extension.sigs.k8s.io/implementations/?h=k8sg#gloo-k8sgateway

[kfswain]

I think these should be fixed in #311 & #338.

Closing for now, If that is not the case, please reopen, thanks!