Update reference docs generation after the repo split

[artberger]

Follow up to #96

• Update kgateway.dev/kgateway sources to agentgateway/agentgateway
  - but 2.2.x is still based off kgateway.dev/kgateway LTS v2.2.x branch
• potentially move to the agentgateway repo so that it can be autogenerated upon release
• investigate if we can automate the version matrix due to more frequent release cycles https://docs.solo.io/agentgateway/2.1.x/reference/versions/
• SBOMs (needs to be created by engineering still)
• OSA (needs to be created by engineering still)
• CVEs (not sure if we scan images today)