Correct some typos in docstrings in cfg.py.
Correct some typos in docstrings in cfg.py.

Change-Id: I3c56596cf0154c342e0a0aa0e60e9111519f3554

citrix-openstack/build-oslo.config,JioCloud/oslo.config,shad7/oslo.config,tianshan/oslo.config,magic0704/oslo.config,metacloud/oslo.config,citrix-openstack-build/oslo.config,varunarya10/oslo.config