Stage 1A - explain import statements

[DylanB5402]

Which page?
https://frcsoftware.org/learning-course/stage1/stage1a/kitbot-drivetrain/

What's wrong?
Stage 1A goes straight into explaining how to set up motor controllers, but omits any explanation of import statements. We should briefly explain what imports are and how to import things quickly in VSCode.

[zachwaffle4]

Imports are explained in stage 0.

[DylanB5402]

We don't need to rehash the entire explanation, but we should at least note that TalonFX/etc come from the CTRE vendordep and give an example of such an import. Same thing for REV