feat(docz): spread remaining props to Props component (#1276)

This commit spreads the remaining props to the user provided `Props`
component. This way, the user can pass custom properties from MDX to
their custom implementation or shadowed component.

core/docz/src/components/Props.tsx

@@ -69,6 +69,7 @@ export interface PropsProps {
   isRaw?: boolean
   isToggle?: boolean
   of: ComponentWithDocGenInfo
+  [key: string]: any
 }
 
 export const getPropType = (prop: Prop) => {
@@ -98,13 +99,15 @@ export interface PropsComponentProps {
   props: Record<string, Prop>
   getPropType(prop: Prop): string
   of: ComponentWithDocGenInfo
+  [key: string]: any
 }
 
 export const Props: SFC<PropsProps> = ({
   title,
   isToggle,
   isRaw,
   of: component,
+  ...rest
 }) => {
   const components = useComponents()
   const { props: stateProps } = React.useContext(doczState.context)
@@ -151,6 +154,7 @@ export const Props: SFC<PropsProps> = ({
       props={props}
       getPropType={getPropType}
       of={component}
+      {...rest}
     />
   )
 }