Review and iterate on the microcopy for the new circuit display

From #152 (closed):

I’d also like to iterate on the descriptive text a little more before we test these, but that shouldn’t hold you up from exploring mobile. I would be happy to come up with some suggestions here, if that helps?

We will need to have at least two versions of the descriptive text, in particular –

1. One for single-path circuits
2. One for multi-path circuits

With an additional conditional portion for onion sites.