Onboarding checklist: Document Linux Foundation trademark reference in the website footers

There is an expectation that the CDF projects reference the Linux Foundation trademark in the footer of the website. Not all projects do it at the moment. It would be nice to update https://github.com/cdfoundation/toc/blob/master/process/new_project_onboarding.md so that it is explicit.

Questions:

* What are the general footer recommendations?
* Which resources need to be updated?
* Is there expectation that distributions also document the trademark if they expose the Web UI?

Start with process/new_project_onboarding.md and review its current onboarding guidance. Determine the general footer recommendations, affected resources, and whether distributions exposing a web UI should document the trademark; the work is done when the file explicitly answers these questions.

Written by the indexing model from the issue text.