fix the remaining spoilers

2012/tromp/how.html

@@ -383,7 +383,7 @@
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-<h1 id="spoiler">Spoiler</h1>
+<h1 id="deobfuscation">Deobfuscation</h1>
 <p>The program implements a so called <a href="https://en.wikipedia.org/wiki/Krivine_machine">Krivine
 machine</a>, enhanced with a <a href="https://en.wikipedia.org/wiki/BIOS">basic
 input/output system</a> and a reference