Add templates for devsite docs builds.

Change-Id: I0bb0238326aed7d2ff931594709cb153b2587061
diff --git a/tools/droiddoc/templates-ds/timestamp.cs b/tools/droiddoc/templates-ds/timestamp.cs
new file mode 100644
index 0000000..4bf502a
--- /dev/null
+++ b/tools/droiddoc/templates-ds/timestamp.cs
@@ -0,0 +1 @@
+var BUILD_TIMESTAMP = "<?cs var:page.now ?>";