fix a typo in format_cpu_spec doc
fix a typo in format_cpu_spec doc

It allow_ranges is true -> If allow_ranges is true

Change-Id: Ia285c1dfb851a652f36e8ce1adb7c0e88853ac3a
Closes-Bug:#1712763

mikalstill/nova,openstack/nova,phenoxim/nova,mahak/nova,gooddata/openstack-nova,mahak/nova,rahulunair/nova,openstack/nova,klmitch/nova,openstack/nova,rahulunair/nova,klmitch/nova,gooddata/openstack-nova,mikalstill/nova,mahak/nova,rahulunair/nova,klmitch/nova,gooddata/openstack-nova,mikalstill/nova,phenoxim/nova,gooddata/openstack-nova,klmitch/nova