Update theme

[mikemckiernan]

This is a doozie to review. I suppose I can break it up into smaller parts if you find it a hassle to review.

[github-actions]

Documentation preview

https://nvidia.github.io/cloud-native-docs/review/pr-142

[a-mccarthy]

Talked with @mikemckiernan about this PR. I think the changes look good.

Some notes on the changes:

• The version picker is not working in the preview b/c it relies on a change to an internal repo that helps to build/publish the docs. This should not be an issue on the live site once everything is merged.
• Updates to using a version1.json file instead of the current version.json file to align with the theme requirements. When we release a new version we only need to update the version1.json file for the new component.
• The code block to create a table of contents is no longer needed for pages. This is handled automatically by the theme.