Term 1, 6.2.2: Active Sensors Typo

[delvingdeep]

There seems to be minor typo in Concept 6: Perception, Module 2: Introduction to 3D Perception and Lesson 2: Active sensor.

The first table is about difference between Active and Passive sensors; but the Table heading are does not match.

The Heading should be Passive Sensors instead of Passive Sensing or the either way Active Sensing and not Active Sensors.

[delvingdeep]

[sahiljuneja]

Fixed. Thanks!