Describe the bug
Add 'labelField' to the frontmatter.json file for a Field Group, the warning "Property labelField is not allowed" is shown for that param. Searching the documentation for 'labelField' doesn't return any results and it is not discussed in the Block or Field Groups section.
https://frontmatter.codes/docs/content-creation/fields#block
https://frontmatter.codes/docs/settings#frontmatter.taxonomy.fieldgroups
This parameter is useful for indicating in a field group which value to show in the list of blocks in a Field Group data structure.