docs($injector): Reword fn param docs and link to DI information

Author: Caitlin Potter

src/auto/injector.js

@@ -147,7 +147,8 @@ function annotate(fn) {
  * @description
  * Invoke the method and supply the method arguments from the `$injector`.
  *
- * @param {!function} fn The function to invoke. The function arguments come form the function annotation.
+ * @param {!function} fn The function to invoke. Function parameters are injected according to the
+ *   {@link guide/di $inject Annotation} rules.
  * @param {Object=} self The `this` for the invoked method.
  * @param {Object=} locals Optional object. If preset then any argument names are read from this object first, before
  *   the `$injector` is consulted.