Fix jwk cache docs (#885)

* Fix example comment

* Upon re-reading, this sentence does not need to exist

examples/jwk_cache_example_test.go

@@ -49,8 +49,7 @@ MAIN:
 			return
 		}
 		_ = keyset
-		// The returned `keyset` will always be "reasonably" new. It is important that
-		// you always call `ar.Fetch()` before using the `keyset` as this is where the refreshing occurs.
+		// The returned `keyset` will always be "reasonably" new.
 		//
 		// By "reasonably" we mean that we cannot guarantee that the keys will be refreshed
 		// immediately after it has been rotated in the remote source. But it should be close\