added a little info on the --simulator parameter

[PierBover]

I added a bit of info on how to open a particular device from the CLI using --simulator.

As a beginner I spent a few hours trying to figure how to open an iPad instead of an iPhone from the CLI.

The CLI doesn't provide any info on how to do that, and I still haven't found any docs describing this.

[ghost]

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[joelcloralt]

@PierBover this is part of the docs now. It was part of this merged PR

[PierBover]

Awesome @joelcloralt this is even better.