Sefer Shmot ends with Moshe putting the Mishkan together, and the Torah describes the Shechina coming down into the Mishkan. 

This would be a fitting end for Sefer Shmot, but for some reason the Torah continues with 3 more Psukim, describing how the Cloud was used to guide Am Israel in the desert, telling them when to leave & travel, and when to stop and park.  

Why does the Torah tells us this now?? 

Why is this the peak of building the Mishkan - and the last Psukim of Sefer Shmot??