Remove an extra dangling doc reference to CDN
Remove an extra dangling doc reference to CDN

This user guide snuck past the effort in
I529c4901e11161158ce5c35df3bff2ecbbb3091a to remove the CDN service. It
was showing up in a warning message during doc builds.

Change-Id: I2670d98078fcdeab5b0cf36a7ff2c0e4b50cbc3b

stackforge/python-openstacksdk,stackforge/python-openstacksdk,briancurtin/python-openstacksdk,openstack/python-openstacksdk,briancurtin/python-openstacksdk,dtroyer/python-openstacksdk,dtroyer/python-openstacksdk,openstack/python-openstacksdk