fix(Accordion): update typings to include AccordionPanel on static props (#3995)

Author: layershifter

src/modules/Accordion/Accordion.d.ts

@@ -2,6 +2,7 @@ import * as React from 'react'
 
 import { default as AccordionAccordion, StrictAccordionAccordionProps } from './AccordionAccordion'
 import AccordionContent from './AccordionContent'
+import AccordionPanel from './AccordionPanel'
 import AccordionTitle from './AccordionTitle'
 
 export interface AccordionProps extends StrictAccordionProps {
@@ -25,6 +26,7 @@ export interface StrictAccordionProps extends StrictAccordionAccordionProps {
 interface AccordionComponent extends React.ComponentClass<AccordionProps> {
   Accordion: typeof AccordionAccordion
   Content: typeof AccordionContent
+  Panel: typeof AccordionPanel
   Title: typeof AccordionTitle
 }