The boundaries of municipal corporations remain as now established unless changed as provided in this title. No charter of any municipal corporation shall contain the metes and bounds of such municipal corporation, but the boundaries shall be incorporated therein by reference to the recordation in the clerk’s office of the court where deeds are admitted to record of the final decree or order of the court establishing such boundaries or the act of the General Assembly by which they are defined. The part of the charter of a municipal corporation defining its boundaries hereafter amended shall not contain the metes and bounds of the municipal corporation, but the boundaries shall be incorporated therein by reference to the recordation of a final decree or order of court or to a General Assembly act.