Fixed a typo in SwiftService API doc
Fixed a typo in SwiftService API doc

Fixed misspelled word in the Service API description.

Change-Id: I0bb6b2aa319ba217dd0d09a2c7a0d8eff9a67aff

sohonetlabs/python-swiftclient,openstack/python-swiftclient,sohonetlabs/python-swiftclient,jeseem/python-swiftclient,openstack/python-swiftclient,jeseem/python-swiftclient