Incorrect docs about the track function

[lucywang000]

In the section The track function of the doc, it says:

The first argument to track should be a named function, i.e not an anonymous one.

But after playing with it a bit, i find it works well with anonymous functions. And from the code, it seems track is storing the cached results in the reagReactionCache attribute of the tracked function object, which shall not preclude the usage of anonymous functions.

(deftype Track [f args ^:mutable reaction]
  IDeref
  (-deref [this]
    (if-some [r reaction]
      (-deref r)
      (cached-reaction #(apply f args) f args this nil)))

(defn- cached-reaction [f ^clj o k ^clj obj destroy]
  (let [m (.-reagReactionCache o)
        m (if (nil? m) {} m)
        r (m k nil)]