[infinispan-dev] New documentation type - Glossary

I've added a new docs category - Glossary. This is for defining terminology we use that new users (and experienced users) might have trouble with. "Data Grid" would be a great example. For each item in the glossary, create a page underneath Glossary, and then we can link it in using an include. An item in the Glossary should use an h2. heading and include the heading in the text body as well as have a page title - this just makes the item reusable.