Fix grammatical error in horizon 'contributing' docs

[Imran Hayder]

While reading 'contributing.rst' in docs folder , i saw a sentence on line 38 that says:
 'Got that all that? '
which doesnt make any sense grammatically, it should be preferably 'Got that all?' or 'Got all of that? '.
here is source : https://git.openstack.org/cgit/openstack/horizon/tree/doc/source/contributing.rst#n38

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/148649

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/148649
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=0ede27a4ded1513aa4f55d9b71a86029e70337e9
Submitter: Jenkins
Branch: master

commit 0ede27a4ded1513aa4f55d9b71a86029e70337e9
Author: imran <email address hidden>
Date: Tue Jan 20 09:06:20 2015 -0800

    Fix grammatical mistake in contributing.rst doc

    There is an extra 'that' in contributing.rst, which doesn't make
    sense for the complete sentence. It should be omitted or written
    in a different way as proposed in the bug description.

    Change-Id: I4757c7948d0ee2701e985ee069ee6b2c5b9e769c
    Closes-Bug: #1412617