Add a testing framework for our docs JS

We are at a point now where we're adding more and more JavaScript code to the docs codebase.

I suggest we add a testing framework to help reduce the risk and improve our code quality.

Benefits

Testing our code has many benefits including:

• Improves code quality.

• Simplifies debugging process (bugs get fixed faster).

• Provides documentation for developers who are unfamiliar with the code.

• Aligns the docs codebase with the product.

• etc.