Allow to override the deployment target

[bitcrumb]

The deployment target can now be set by specifying it in the liftoffrc file, it will override the default of LATEST_IOS

[gfontenot]

Nice! Feel like getting your hands dirty and learning mdoc? If we're letting this be specified in the liftoffrc, we should add it to the documentation in liftoffrc(5).

[bitcrumb]

Sure, good point. I'll have a look at it! Reminds me that I should do the same for the --[no-]settings cli option added in #191.

[gfontenot]

Ah, yeah, that should be added to liftoff(1). That one should be easier. I'll merge this if you want to open a new PR with the documentation changes?

[bitcrumb]

Go ahead, will do.

[gfontenot]

Merged in 802956a

[bitcrumb]

Done, see #202.