Link Japanese translation (#11)

See triple-underscore/triple-underscore.github.io#1 (comment).

Author: domenic

index.bs

@@ -7,6 +7,7 @@ Abstract: communications with server-side processes.
 Indent: 1
 Markup Shorthands: markdown yes
 Text Macro: TWITTER whatsockets
+Translation: ja https://triple-underscore.github.io/WebSocket-ja.html
 </pre>
 
 <pre class=biblio>