[DDW-923] Add comment for re callback usage

Author: Lucas Araujo

source/renderer/app/components/staking/stake-pools/hooks/useInViewPort.tsx

@@ -11,6 +11,8 @@ export const useInViewPort = () => {
     })
   );
 
+  // React will call the ref callback twice. Once when the component mounts, and call it with again when it unmounts.
+  // https://reactjs.org/docs/hooks-faq.html#how-can-i-measure-a-dom-node
   const setTargetRef = useCallback((target: HTMLElement) => {
     if (targetRef.current) {
       observerRef.current.unobserve(targetRef.current);