Upgrade matrix Documents

[dyadav-r7]

I was upgrade from 18.x to 21.x and knativeserving is giving upgrade error

message: 'Version migration is not eligible with message: not supported to upgrade
        or downgrade across multiple MINOR versions. The installed KnativeServing
        version is v1.18.0'
      reason: Error
      status: "False"
      type: Ready
    - lastTransitionTime: "2026-01-28T07:27:44Z"
      message: 'Version migration is not eligible with message: not supported to upgrade
        or downgrade across multiple MINOR versions. The installed KnativeServing
        version is v1.18.0'
      reason: Error
      status: "False"
      type: VersionMigrationEligible

is the any documentation mentioning supported upgrade path?