docs: add redirect for download.html

Change-Id: Id54f1899c1933796524d6c2b5e991a652b354287
diff --git a/docs/html/sdk/download.jd b/docs/html/sdk/download.jd
new file mode 100644
index 0000000..81b4ff6
--- /dev/null
+++ b/docs/html/sdk/download.jd
@@ -0,0 +1,4 @@
+sdk.redirect=true
+
+@jd:body
+