[FLINK-39451][release] Mark the 2.2 docs as outdated

[alpinegizmo]

With the release of 2.3.0, the docs for 2.2 become outdated.

These docs should have been linked from the home page, fixing that too.

[flinkbot]

CI report:

• e0cb1d0 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build

[lihaosky]

There is CI failure

ERROR [zh] REF_NOT_FOUND: Ref "/release-notes/flink-2.2.md": "/home/vsts/work/1/s/docs/content.zh/_index.md:1:1": page not found
Total in 21646 ms
Error: error building site: logged 1 error(s)
Error building the docs

[RocMarshal]

Thanks @alpinegizmo