pub fn set_field(
text: &str,
field: &str,
value: &str,
) -> Result<(String, bool), String>Expand description
Set or update a top-level scalar frontmatter field on a concept’s text,
preserving every other byte. Returns the new text and whether an existing key
was replaced (false means a new key was appended before the closing fence).
Errors when the text has no frontmatter to edit.