Rewrite website docs to refer to smart-proxy rather than capsule
We're seeing IRC users trying to understand how capsules relate to smart-proxies, in some case believing them to be different things that maybe can't co-exist. That's obviously not the case, since they're effectively the same thing, it's just a branding issue.
We should rewrite our upstream docs to stick to smart-proxy, and keep capsule as a downstream term, to ensure a clean separation. This may need a little work in hammer too (some commands refer to capsules) but we can always track that under a sub ticket.