Create a Sphinx Glossary for terms

[djwfyi]

Is your feature request related to a problem? Please describe. N/A

Describe the solution you'd like Sphinx supports a glossary, as described at

• https://sublime-and-sphinx-guide.readthedocs.io/en/latest/glossary.html
• https://www.sphinx-doc.org/en/master/usage/restructuredtext/directives.html#directive-glossary

Steps to implement:

1. Create a file to hold the glossary directive and contents, such as glossary.rst
2. Add terms to the glossary file
3. Create links to the terms by adding the :term: <word> directive to docs content