Warn about JDK9

Change-Id: Ib852cde3e959f61fc2c96650535353c0b137c212
Reviewed-on: https://asterix-gerrit.ics.uci.edu/2179
Reviewed-by: Xikui Wang <xkkwww@gmail.com>
diff --git a/content/download.html b/content/download.html
index ba714e9..69a0142 100644
--- a/content/download.html
+++ b/content/download.html
@@ -106,6 +106,8 @@
     <div class="row">
 <div class="col-md-8 col-centered">
 <h2>Download</h2>
+<p>Please note that version 0.9.2 requires Java 8; Java 9 will not work.</p>
+
 <div class="row">
 <div class="col-md-6">
     <h3 id="source">Source</h3>
diff --git a/download.md b/download.md
index 3401a19..92b25b9 100644
--- a/download.md
+++ b/download.md
@@ -2,6 +2,8 @@
 title: Download
 ---
 
+Please note that version 0.9.2 requires Java 8; Java 9 will not work.
+
 <div class="row">
 <div class="col-md-6" markdown="1">
 ### Source