Tweak Javadoc for mute keycode constants

Tweak documentation so that it doesn't imply that the platform
implements default behavior for the microphone mute key.

Bug: 204908779
Change-Id: I9aa53623854f5f62f873f7bb2c4a1f64c7025c56
diff --git a/core/java/android/view/KeyEvent.java b/core/java/android/view/KeyEvent.java
index 1460cb2..c3a638c 100644
--- a/core/java/android/view/KeyEvent.java
+++ b/core/java/android/view/KeyEvent.java
@@ -295,7 +295,8 @@
     /** Key code constant: Fast Forward media key. */
     public static final int KEYCODE_MEDIA_FAST_FORWARD = 90;
     /** Key code constant: Mute key.
-     * Mutes the microphone, unlike {@link #KEYCODE_VOLUME_MUTE}. */
+     * Mute key for the microphone (unlike {@link #KEYCODE_VOLUME_MUTE}, which is the speaker mute
+     * key). */
     public static final int KEYCODE_MUTE            = 91;
     /** Key code constant: Page Up key. */
     public static final int KEYCODE_PAGE_UP         = 92;
@@ -482,9 +483,10 @@
     /** Key code constant: Numeric keypad ')' key. */
     public static final int KEYCODE_NUMPAD_RIGHT_PAREN = 163;
     /** Key code constant: Volume Mute key.
-     * Mutes the speaker, unlike {@link #KEYCODE_MUTE}.
-     * This key should normally be implemented as a toggle such that the first press
-     * mutes the speaker and the second press restores the original volume. */
+     * Mute key for speaker (unlike {@link #KEYCODE_MUTE}, which is the mute key for the
+     * microphone). This key should normally be implemented as a toggle such that the first press
+     * mutes the speaker and the second press restores the original volume.
+     */
     public static final int KEYCODE_VOLUME_MUTE     = 164;
     /** Key code constant: Info key.
      * Common on TV remotes to show additional information related to what is