Add libraries information

[davepagurek]

• Adds more categories
• Adds extra metadata
• Makes an images subdirectory for libraries assets (I put this outside of /public so it can be optimized, but just to confirm, is this cool?)
• Adds a readme for contributing libraries

[stalgiag]

Looks great! This is the kind of work you can feel free to merge yourself as long as the changes to the schema don't break the build process.

[davepagurek]

Sounds good, thanks for the confirmation!