Additional expansion of landing page

[caufieldjh]

Would like to have live updates for:

• project names, repos, and file locations
• all graph objects, based on the MANIFEST
• graph metadata re: validation status

Also would like to include:

• additional documentation re: KG-Hub ecosystem
• basic instructions for new KG-Hub projects

[caufieldjh]

Also would like to make it so the page doesn't say "Knowledge Graph Hub" five times

[caufieldjh]

Addressed some of this in #41