This function removes the Docker images used
for rendering the R Markdown document based on the output
YAML file from the (possibly unsuccessful) rendering process.
Usage
prune_image(input_yml)
purge_image()
Arguments
input_yml
The YAML file path (output of render_docker)
when prune_info = TRUE which stores the information of the
Docker image to be removed. If not specified, will prune all
dangling images.