Add canonical startpoint link to cookieplone make commands docs to the initial console output

[acsr]

A canonical startpoint link to the detailed cookieplone make commands docs (under development, but ready soon) could be already mentioned in the initial console output of a cookieplone run
This accompanies the related ticket in the cookieplone-templates repository:
plone/cookieplone-templates#197

It depends on a design decision where to put this (both locations in the console output are possible and useful with different wording.

The canonical startpoint link to this detailed cookieplone make commands docs (when initially available to docs) should be mentioned in the final console output of a cookieplone run and the main README.md.

I enjoyed the extended explanation @sneridagh used in the final console output of his seventemplate branch/tag. This is the first place to avoid confusion for newbies.

Originally posted by @acsr in #1758

[stevepiercy]

I think that the console output should only reference the project root README.md as canonical. This will avoid adding a maintenance burden of keeping duplicate information in sync.

In the project root README.md, we can add a link to the recently published docs at https://6.docs.plone.org/reference-guide/cookieplone-make-commands.html.