CDK-767: Update CLI docs for 0.17.1 changes.

This adds a description of how csv-schema infers types, handles
nullability, and sets default values. This also adds the --require
option.

Adds a warning about how records are validated to csv-import.
CDK-751: Add Kite start page as index.html.

This includes Dennis's edits from CDK-751.

The existing index has been moved to all-pages.md. This needs to be
improved before committing, possibly by organizing all pages and adding
a sidebar rather than using all-pages directly.