www-apps/zola: add cjk USE flag metadata

Fixes: 93f5518e5
Signed-off-by: zyxhere💭 <zyx@envs.net>

www-apps/zola/metadata.xml

@@ -5,6 +5,9 @@
       <email>zyx@envs.net</email>
       <name>zyxhere💭</name>
     </maintainer>
+    <use>
+       <flag name="cjk">Enable indexing ja and zh languages</flag>
+    </use>
     <upstream>
       <bugs-to>
         https://github.com/getzola/zola/issues