merge in old CLs to new jd files

Change-Id: Iee99364f6a99270fee5f4fdb766ec39fb51a74d1
diff --git a/src/devices/tech/input/key-layout-files.jd b/src/devices/tech/input/key-layout-files.jd
index d416341..63fbcac 100644
--- a/src/devices/tech/input/key-layout-files.jd
+++ b/src/devices/tech/input/key-layout-files.jd
@@ -52,10 +52,16 @@
 and flags.</p>
 <h3 id="key-declarations">Key Declarations</h3>
 <p>Key declarations each consist of the keyword <code>key</code> followed by a Linux key code
-number, an Android key code name, and optional set of whitespace delimited policy flags.</p>
-<pre><code>key 1     ESCAPE
+number and an Android key code name, or the keyword `usage` followed by a HID
+usage and an Android key code name. The HID usage is represented as a 32-bit
+integer, where the high 16-bits represent the HID usage page and the low
+16-bits represent the HID usage ID. Either of these declarations can then be
+followed by an optional set of whitespace delimited policy flags.</p>
+<pre><code>
+key 1     ESCAPE
 key 114   VOLUME_DOWN       WAKE
 key 16    Q                 VIRTUAL     WAKE
+key usage 0x0c006F          BRIGHTNESS_UP
 </code></pre>
 <p>The following policy flags are recognized:</p>
 <ul>