Every time I try to share a post, my profile avatar image gets automatically added to the preview. However, I want to be able to customize this image based on the specific post I am making. I already tried a host of different things (i.e., specifying image: " " in the rmarkdown file itself, updating config.toml, placing the image in the static/img folder, etc.), but to no avail. Can anyone here please help me with specific instructions on how to do this?