Pedantic language change (#500)

* Pedantic language change

This page led to the creation of a bad question on a job interview test, leading someone to believe that functions and objects are primitives. They are not.

https://developer.mozilla.org/en-US/docs/Glossary/Primitive

* Verbiage change

content/docs/typechecking-with-proptypes.md

@@ -40,7 +40,7 @@ Here is an example documenting the different validators provided:
 import PropTypes from 'prop-types';
 
 MyComponent.propTypes = {
-  // You can declare that a prop is a specific JS primitive. By default, these
+  // You can declare that a prop is a specific JS type. By default, these
   // are all optional.
   optionalArray: PropTypes.array,
   optionalBool: PropTypes.bool,