add hybrid browser and disruptor test

[mdcruz]

Also updates the README for more instructions

[dgzlopes]

I like the shape this is taking. Thanks, @mdcruz!

One problem with the current directory organization is that all scripts that import the example data or the shared/frontend module are broken. Also, it is hard to follow with folders inside folders.

Any thoughts on:

• /k6
  • /foundations
    • /data
    • /lib (rename of the current shared folder)
    • /extension
    • all main tests
  • /browser (specific tests / deep dive)
  • /disruptor (specific tests / deep dive)
  • /extra/misc/something (hybrid tests, WebSockets example, and more future things, tracing etc.) - not sure about the name.

That way, someone running the main track can live in their folder without many jumps. But, if they want to fork the session in the middle and go to another, more specific track, they can too!

[mdcruz]

@dgzlopes I've made more changes. Can you review it again, please? :) Thanks!