add comment

packages/shared/hooks/useEffectSingleThreaded.tsx

@@ -1,6 +1,9 @@
 import { useEffect, useRef } from 'react';
 import { isPromise } from '../utils';
 
+// useEffectSingleThreaded is a useEffect that will only run one at a time, and will
+// caches the latest deps of requests that come in while it is running, and will
+// run that after the current run is complete.
 export default function useEffectSingleThreaded(
     fn: (deps) => void | Promise<void>,
     deps: any[]