Remove duplicate code in quickstart docs

Signed-off-by: Roald Nefs <info@roaldnefs.com>

Author: roaldnefs

docs/user/quickstart.rst

@@ -70,7 +70,6 @@ Using the
 service we can retrieve all domains in your TransIP account in the form of a
 :class:`Domain <transip.v6.objects.Domain>` object::
 
-    >>> domains = client.domains.list()
     >>> domains = client.domains.list()
     >>> for domain in domains:
     ...     print(domain)