Recommend arrival rate with examples

While there is currently a page on what [arrival rate](https://k6.io/docs/using-k6/scenarios/arrival-rate) is and why it is better, it isn't really recommended through the documentation, so a lot of users will be unlikely to use it.

I would argue that also there should be an even more in-depth documentation/blog post/examples showing how arrival rate makes the difference between testing the SUT and playing along with it.