Parshas Re'eh: What is the Meaning of לְשִׁכְנוֹ תִדְרְשׁוּ וּבָאתָ שָׁמָּה?

How exactly did they later discover the site of the בֵּית הַמִּקְדָּשׁ? After all, it is not stated in the חֻמָּשׁ?