Docs: Add CDD link to Downloads page

Bug: 23360409
Change-Id: I3af1e6e15829bae29ee199c208d7255259fc8725
diff --git a/src/compatibility/downloads.jd b/src/compatibility/downloads.jd
index e88a6ce..9eb072a 100644
--- a/src/compatibility/downloads.jd
+++ b/src/compatibility/downloads.jd
@@ -32,6 +32,8 @@
 The source code for the following tests can be synced with the
 'android-cts-6.0_r1' tag in the open-source tree.</p>
 <ul>
+<li><a href="6.0/android-6.0-cdd.pdf">Android 6.0 Compatibility Definition
+Document (CDD)</a></li>
 <li><a
 href="https://dl.google.com/dl/android/cts/android-cts-6.0_r1-linux_x86-arm.zip">Android
 6.0 R1 Compatibility Test Suite (CTS) - ARM</a></li>