Maybe a missing feature; not sure.
How would we go about adding the site/project logo top left in a ReadTheDocs site using the MkDocs engine?
At https://sphinx-rtd-theme.readthedocs.io/en/latest/configuring.html#adding-a-logo (and some SO questions) it appears configuring logo is unrelated to RTD or MkDocs but is actually targeting the Sphinx RTD theme.