* replace sample IPv4/IPv6 addresses with reserved ones from RFC-6890
* remove initial blank line: prevents github from rendering the .rst
* emphasize --hostname, then have --port/--location as a special-case
* list --port first (describe it "from the inside out"), then --location
* explain difference between --port and --location
* in endpoint strings, put interface= at end, to emphasize port
* add servers.rst to index.rst so it'll show up on readthedocs
* don't mention "partial-cone NAT": that's only relevant if/when we get
real ICE-style NAT-hole-punching
460cc826fd
