function updateREADME( signatures ) {
	var parts;
	var file;
	var docs;
	var out;
	var err;
	var i;

	file = readFile( README, FOPTS );
	if ( file instanceof Error ) {
		throw file;
	}
	docs = [];
	for ( i = 0; i < signatures.length; i++ ) {
		docs.push( createDoc( signatures[ i ] ) );
	}
	out = [];
	parts = file.split( '\n<!-- charcodes -->' );
	out.push( parts[ 0 ] );
	out.push( '<!-- charcodes -->' );
	out.push( '' );
	out.push( charCodeList( DTYPES ).join( '\n' ) );
	out.push( '' );

	parts = parts[ 1 ].split( '<!-- ./charcodes -->\n' );
	out.push( '<!-- ./charcodes -->' );

	parts = parts[ 1 ].split( '\n<!-- loops -->' );
	out.push( parts[ 0 ] );
	out.push( '<!-- loops -->' );
	out.push( '' );
	out.push( docs.join( '\n' ) );

	parts = parts[ 1 ].split( '<!-- ./loops -->\n' );
	out.push( '<!-- ./loops -->' );
	out.push( parts[ 1 ] );

	err = writeFile( README, out.join( '\n' ), FOPTS );
	if ( err ) {
		throw err;
	}
}
Update the package README.

@private
@param {StringArray} signatures - list of (sorted) loop signatures
@throws {Error} unexpected error