Provide attribution consistently in the Construction Structure and maybe Markdowns

[orcmid]

The construction-structure text files have copyright notices and Apache license grants. For consistency with CC-BY, an attribution statement needs to always be present on how these works can be referenced from derivatives made by ohers.

This does not restrict authors to this with respect to their own copyright works, although there are useful cases of self-attribution being a good accountability practice.

[orcmid]

this applies to

• docs/docs.txt
• docs/index.md (maybe?)
• docs/about/about.txt
• docs/about/index.md
• docs/construction/construction.txt
• docs/construction/index.md
• docs/construction/current/current.txt
• docs/construction/current/index.md
• docs/construction/plain/plain.txt
• docs/construction/plain/index.md

[orcmid]

Most construction struccture is accomplished by copy, paste, and edit (or open, save-as, edit). So once that is the practice, expansions will already have an attribution entry that can be modified for the new file.