function onContents( error, contents ) {
		if ( error ) {
			debug( 'Encountered an error: %s', error.message );
			return clbk( error );
		}
		debug( 'Read %d README.md files', contents.length );
		clbk( null, toc( contents, aliases, opts.blacklist ) );
	}
Callback invoked after loading `README.md` files.

@private
@param {(Error|null)} error - error object
@param {(EmptyArray|StringArray)} contents - README.md contents
@returns {void}