[glossary] fixed a grammar error
[glossary] fixed a grammar error


Closes-Bug: #1605190
Change-Id: I08573fbcb1ae97a55a38cdfadc2299645e6decfb

AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals