Add documentation comments at the top of the SonarLights example sketch

These comments should do four things:

1. Describe the function of the sketch. What does it do (in broad terms)?
2. Describe what hardware it uses, Ethernet shield?, Certain model of Sonar unit, NeoPixel lights?
If there are possible restrictions on which kind of Arduino it can run on (does it need Mega because it needs lots of memory?
3. Describe how it gets hooked up? e.g. Connect the neopixel string to NEO_PIN and the left sonar unit to LEFT_SONAR_PIN, etc... (pick good names to make that easy)
4. Describe what library modules the user should have installed in order to build this sketch.
eg. Arduino1076, ArduinoJson, AdaFruit_Neopixel