Bugs found when converting the docker-introduction repo

[multimeric]

• Objectives in the introduction (index.md) are ported, but the new workbench doesn't actually render these. Should these objectives just be deleted? e.g. https://github.com/carpentries-incubator/docker-introduction/blob/15b3b4ff4f31b542d6b522262f3561ce69cb0801/index.md?plain=1#L8-L20
• Links that have a name rather than a URL get copied verbatim, and then fail: https://github.com/carpentries-incubator/docker-introduction/blob/15b3b4ff4f31b542d6b522262f3561ce69cb0801/index.md?plain=1#L49. I assume these link names reference a URL elsewhere in the document. Can these be dereferenced?