fixed some miss communication about _replicator
fixed some miss communication about _replicator

Was saying to `PUT` to `_replicator` directly.
Which throws a "database exists" or similar error.

Also tweaked intro copy to be clearer.

Signed-off-by: Alexander Shorin <287dfd97d2274fe201ae7191a244ba25e475e13a@apache.org>

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb