Clarify Fragment#onHiddenChanged() documentation.

Prior comment said that fragment was hidden for both true and false
values of hidden.

This is support library version of ag/1116166

Bug:
https://code.google.com/p/android/issues/detail?id=53178

Change-Id: I2f4b5e6f3140caa32b30309624c23018928358ce
diff --git a/fragment/java/android/support/v4/app/Fragment.java b/fragment/java/android/support/v4/app/Fragment.java
index 07aea7c..36afd9b 100644
--- a/fragment/java/android/support/v4/app/Fragment.java
+++ b/fragment/java/android/support/v4/app/Fragment.java
@@ -806,8 +806,7 @@
      * Called when the hidden state (as returned by {@link #isHidden()} of
      * the fragment has changed.  Fragments start out not hidden; this will
      * be called whenever the fragment changes state from that.
-     * @param hidden True if the fragment is now hidden, false if it is not
-     * visible.
+     * @param hidden True if the fragment is now hidden, false otherwise.
      */
     public void onHiddenChanged(boolean hidden) {
     }