[DOC]: Update cuGraph website for cuda 12

[acostadon]

How would you describe the priority of this documentation request

High

Please provide a link or source to the relevant docs

https://docs.rapids.ai/api/cugraph/nightly/installation/getting_cugraph/

Describe the problems in the documentation

All installation docs refer only to cuda 11.

• [ ] Add references to cuda 12
• [ ] Correct cuda 11 references with the valid versions
• [ ] check for required changes in docker container

(Optional) Propose a correction

No response

Code of Conduct

• [X] I agree to follow cuGraph's Code of Conduct
• [X] I have searched the open documentation issues and have found no duplicates for this bug report