Fix typo in jsdoc comment; flip "objects are keys" to "keys are objects" (#265)

* Update index.d.ts
* add changeset

Co-authored-by: Saihajpreet Singh <saihajpreet.singh@gmail.com>

Author: dhritzkiv

.changeset/great-swans-ring.md

@@ -0,0 +1,5 @@
+---
+"dataloader": patch
+---
+
+Fix typo in jsdoc comment; flip "objects are keys" to "keys are objects"

src/index.d.ts

@@ -106,7 +106,7 @@ declare namespace DataLoader {
 
     /**
      * Default `key => key`. Produces cache key for a given load key. Useful
-     * when objects are keys and two objects should be considered equivalent.
+     * when keys are objects and two objects should be considered equivalent.
      */
     cacheKeyFn?: (key: K) => C,