Correct documentation of _decode_link method.
Correct documentation of _decode_link method.

It returns a bare tuple, not a named RiakLink tuple.
GabrielNicolasAvellaneda/riak-python-client,basho/riak-python-client,GabrielNicolasAvellaneda/riak-python-client,basho/riak-python-client,bmess/riak-python-client,bmess/riak-python-client,basho/riak-python-client