fix incorrect prop types recognition

[CiotkaCierpienia]

This fix warnings:

• Warning: Failed prop type: Content: prop type headerProps is invalid; it must be a function, usually from the prop-types package, but received object.This often happens because of typos such as PropTypes.function instead of PropTypes.func.
• Warning: Failed prop type: Content: prop type paragraphProps is invalid; it must be a function, usually from the prop-types package, but received object.This often happens because of typos such as PropTypes.function instead of PropTypes.func.
• Warning: Failed prop type: Content: prop type youTubeEmbedProps is invalid; it must be a function, usually from the prop-types package, but received object.This often happens because of typos such as PropTypes.function instead of PropTypes.func.
• etc.

Caused by compilation of propTypes as function instead of object