what to do with the FE-knowledgebase repo + its CMS once resource library is ready to replace it

[erichuffman]

Once the resource library Storybook instance is in good enough shape we should consider what to do with the FE-knowledgebase repo.

Considerations:

• should we archive the repo (plus its Strapi CMS repo?)
• should any further work be done to the KS site to note it's deprecated, such as a site-wide header update with a message noting it's deprecated?