preamble-discussions-to

# `preamble-discussions-to`

The `discussions-to` header is a valid URL.

## Examples

    error[preamble-discussions-to]: preamble header `discussions-to` is not a valid URL
     --> input.md:6:16
      |
    6 | discussions-to: not a website dot com
      |                ^^^^^^^^^^^^^^^^^^^^^^ relative URL without a base
      |

## Explanation

`preamble-discussions-to` makes sure that the `discussions-to` front matter (or preamble) header is a correctly formatted URL.