I have not been able to tweak the solutions on this Stack Overflow page so that a couple images appear on my Github page (README). Most of my images appear just fine and they are all in the repository base folder.
I only see a link that does not work rather than an image for cases like "R Project image" even though the URL looks essentially the same as the URLs for images that do appear. All images appear correctly when I knit on my computer, but the Github results are not changing after I push the committed work out.
The Stack Overflow answers refer to adjusting the base.url argument of knitr$set. I also have not found a successful solution in https://happygitwithr.com/.