List the available template by name that can be used with draft() to create
a new document for R Markdown from a package.
available_templates(package = "rmarkdown", full_path = FALSE)A character vector of templates name to use within draft(). If
full_path = TRUE, it returns the full path to the templates.
# List rmarkdown templates & create a draft
available_templates()
#> [1] "github_document" "html_vignette"
# List rticles templates
available_templates("rticles")