docs: Prefer const to let (auto generating selectors) (#3094)

Author: vikpe

docs/guides/auto-generating-selectors.md

@@ -23,9 +23,9 @@ type WithSelectors<S> = S extends { getState: () => infer T }
 const createSelectors = <S extends UseBoundStore<StoreApi<object>>>(
   _store: S,
 ) => {
-  let store = _store as WithSelectors<typeof _store>
+  const store = _store as WithSelectors<typeof _store>
   store.use = {}
-  for (let k of Object.keys(store.getState())) {
+  for (const k of Object.keys(store.getState())) {
     ;(store.use as any)[k] = () => store((s) => s[k as keyof typeof s])
   }