[15/09/21] Added section Sensors in Electronics, added a page on Lidar to Sensors

[TheRandomizer7]

Main changes

1. Added section of Sensors in Electronics
2. Added Lidar page in Sensors
3. Added images folder to the Sensors folder and added 4 images

Lidar contents

1. Definition of Lidar
2. How Lidar works
3. Types of Lidar
4. Components of Lidar
5. Lidar usage with ROS
6. Applications of Lidar
7. Companies working on Lidar

[veds12]

Make it "[15/09/21] Added section ......".
@pranavgo can look into automating this