Added core typings and usage examples to social-urls and schema-org

[vikaspotluri123]

no issue

• Added basic type hints and usage examples to the social-urls package
• Added a usage example and data structure to the schema-org README
• Added JSDoc types to schema-org
  • I did my best with this, but there might be a couple of issues. A typings (.d.ts) file would work better since JSDoc doesn't really have support for function overloading, but I figured that would add to the maintenance overhead