This function adds or updates the License badge to the README.Rmd.
This function reads the License field of the DESCRIPTION file. Ensure
that this field is correctly defined. See add_license() for further detail.
This function requires the presence of a DESCRIPTION file at the project
root. See add_description() for further detail.
Make sure that 1) a README.Rmd file exists at the project root and 2) it
contains a block starting with the line <!-- badges: start --> and ending
with the line <!-- badges: end -->.
Don't forget to re-render the README.md.
See also
Other adding badges:
add_codecov_badge(),
add_cran_badge(),
add_dependencies_badge(),
add_github_actions_check_badge(),
add_github_actions_codecov_badge(),
add_github_actions_pkgdown_badge(),
add_lifecycle_badge(),
add_repostatus_badge()
