Adds glossary to training guides

Glossary is added to training gudies. This glossary is in sync with
openstack manuals and should not be updated here. For any changes to
the glossary, please make them under openstack-manuals repository.
Glossary will be automatically updated from the openstack-manuals
repository.

Change-Id: I9c1da0d2d8cec4c128b85eeed687ff1d853b6929