Fixed grammatical mistake
Fixed typo where .com was added twice
Merge pull request #1188 from Imdsm/patch-2

docs(using): fixed typo where .com was added twice
Merge pull request #1187 from Imdsm/patch-1

docs(installing): fixed grammatical mistake
fix(registry): Setup registry cache properly

Start deis-cache before starting deis-registry and grant
deis-registry access to the /deis/cache etcd key space

Fixes https://github.com/deis/deis/issues/1120