Add definition

packages/website/ts/globals.d.ts

@@ -8,6 +8,7 @@ declare module 'react-flickity-component';
 declare module 'react-anchor-link-smooth-scroll';
 declare module 'react-responsive';
 declare module 'react-scrollable-anchor';
+declare module 'react-headroom'
 
 declare module '*.json' {
     const json: any;