convert spoiler language and towards deobfuscation language

1994/horton/index.html

@@ -429,7 +429,7 @@ newsletter and a PDF file of just the pages cited.</p>
 <p>Run it with any 4 numeric arguments, e.g. <code>./horton 3 2 1 0</code>. Play with the
 numbers to get a pleasing result, or use it for your high school algebra
 class.</p>
-<h3 id="spoiler">SPOILER:</h3>
+<h3 id="deobfuscation">DEOBFUSCATION:</h3>
 <p>As should be obvious from 20 feet away, the program is a cubic plotter.
 It plots against certain artists, splattering their cubes with graphs
 of their cubic equations. Those dastardly arguments are mere coefficients,