convert spoiler language and towards deobfuscation language

2015/endoh2/index.html

@@ -431,7 +431,7 @@ Location: <a href="../../location.html#JP">JP</a> - <em>Japan</em></li>
 <p>Hint 1: Do <code>less prog.c</code>. You will see an <strong>emphasized</strong> string if your
 terminal supports bold.</p>
 <p>Hint 2: Do <code>wc -c prog.c</code>. This is very long one-liner.</p>
-<p>Spoiler: Open the source with an editor like <code>vim</code> or <code>emacs</code>.</p>
+<p>Deobfuscation hint: Open the source with an editor like <code>vim</code> or <code>emacs</code>.</p>
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