Needs approval from an approver in each of these files:
- ~~[OWNERS](https://github.com/janus-idp/janus-idp.github.io/blob/main/OWNERS)~~ [BethGriggs]
Approvers can indicate their approval by writing `/approve` in a comment
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What does this PR do / why we need it
This PR adds a banner to all blog posts indicating the content is archived in order to avoid users from attempting to use legacy content and tutorials
Which issue(s) does this PR fix
Fixes https://issues.redhat.com/browse/RHIDP-2896
PR acceptance criteria
How the banner looks: