Updates to address items listed in issue 63

[mkavulich]

• Clean up Glossary and linked terms
• Replace mentions of forum with GitHub discussions
• Updates to host side coding based on changes to CCPP Physics
• Update Code Management for new Application Fork workflow
• Some miscellaneous fixes

You can view the latest version of this branch's proposed changes in ReadTheDocs here: https://mike-k-tech-doc.readthedocs.io/en/latest/index.html

[mkavulich]

@ligiabernardet Thank you for the thorough reivew! I believe I have addressed all the changes you requested, let me know if you have more comments.