Implement Android setup instructions in the expo config plugin

[Upsilon-Iridani]

Is your feature request related to a problem? Please describe.
#355

Describe the solution you'd like
The stripe config plugin should (optionally?) implement the setup instructions outlined in docs/android-chrome-tab-closes-on-background.md

Describe alternatives you've considered
Writing the config myself.

Additional context
I'm guessing every expo user of the library deals with the same setup hassle?

[Upsilon-Iridani]

I made a draft, but I think more eyes are needed on this one. Thoughts?

[gbirch-stripe]

@Upsilon-Iridani thanks for opening a pull request! We will be sure to take a look at it