* Update README.md

Add a new section (Announcements)

* Update README.md

Remove description columns from tables
Remove guidelines sections

* Update CONTRIBUTING.md

Add a link to the wiki for guidelines

* Create README_TEMPLATE.md

Add a README template file for a new model

* Create pull_request_template.md

Add a new template for a pull request

* Update README.md

Add a table of contents
Add a new section for archived models and implementations

* Update README.md

Revise "Contributions"

* Update README.md

Update the link to the contribution guidelines

* Update README.md

Update the link to the contribution guidelines.

* Update README.md

Update the link to the contribution guidelines.

* Update README.md

Update the link to the contribution guidelines.