As of now, the glossary defined in our documentation reflects the
current state of the codebase. In order to avoid any discrepancy
between the codebase and each definition, the objective here is to
gather both in a single place and link it into the rst documentation
via a custom directive.
Also re-aligned the requirements with liberty for doc.
Change-Id: I3089fd9f948b948115672f10937b1500b96ce180
Partial-Bug: #1526671
Move glossary.rst from /doc/dev to /doc/ as glossary is not only
related to dev. Updated index.rst.
Change-Id: I2e5251bdb0b94ef03727dea26bc43866544d2fd3
Closes-Bug: #1527130
