New rolling + stable aigw version policy

[jbaross]

Definition of done

Updates https://developer.konghq.com/ai-gateway/version-support-policy/#versioning to reflect https://docs.google.com/document/d/1RXnYdoBpjePjQZ_rkbEgvqUgpoGy6_hXWDycfSXWLwM/edit?tab=t.0#heading=h.t650t1l4veom with 2.2 as the first stable version.

Greg is the main author of the new policy and should review this to ensure the intent is preserved.

Information

Size

• M (Medium) Example: writing a UI how to for a straightforward product, adding a plugin example

[jbaross]

PR: #7386

[tomek-labuk]

Waiting for Greg/Legal to work out the minimum viable number of days to alert customers to a change prior to executing.