Fix Bugs in Examples Using Line Following Sensors

- Update experiment 2 and 3 with improved line following examples for  with option to debug via MakeCode console. Previous examples did not actually read a dark surface correctly...
- Add some animated arrows for the user to see what button to press when the micro:bit initializes
- Include notes for each condition statement
- Broke up experiment 3 into two parts for users to easily digest.
- Update battle bot example so it does not randomly "attack" based on line following readings on "collision." That's not how line following sensors work...