Reword the recent deobfuscation changes

In most cases the word was changed to 'obfuscation' as it was about
obfuscation, not deobfuscation. In some cases like 1995/leo since the
file was (in 1995/leo) about a secret switch it was changed to
'secret.md' (and 'secret.html') but there were others like that as well.

One entry had the words 'spoiling the size rule' but this had been
changed to 'deobfuscating the size rule' which was obviously wrong.

In the latter YYYY/README.md files the judges had written after some
entries (brief summaries) '...

    ...We'll stop spouting spoilers now. Have fun exploring all the
    entries!

but that was changed to:

    ...We'll stop spouting deobfuscation information now. Have fun
    exploring all the entries!

which wasn't really about deobfuscation but just a brief summary of what
the entries did.

And in the most problematic case (at least for me :-), 2018/ferguson) I
had put a joke in:

    ... but it's the only Easter egg I won't spoil

but it was changed to 'won't deobfuscate' which not only is not what it
is but it spoilt the joke.

In some cases the word was changed back to 'SPOILER' (or similar) but in
most cases not. I believe it should be better now. There are some
caveats, however, as below.

Although make find_missing_links is okay I do not remember if this will
catch links that refer to '%%REPO_URL%%' or other pandoc tokens. This
means I might have to go back to some earlier years to verify links are
okay. That should not take that much time I hope.

It might also be that some wording can still be improved some but it is
hoped this will be discovered when checking links and looking over the
manifest (which obviously changed).

2006/monge/README.md

@@ -248,7 +248,7 @@ changing the definitions of `W`, `H` and `I` at the beginning of the code.
   parameter.
 
 
-### Deobfuscation
+### Obfuscation
 
 Sure, I don't want to deprive you of the pleasure of digging
 into the infernal mess created by my corrupted mind (writing
@@ -262,9 +262,9 @@ of how all the program works to be worked out).
 
 This program is a formula parser that outputs machine code that
 calculates the formula and check the given conditions. The
-machine code targets the x87 stack based
+machine code targets the `x87` stack based
 [FPU](https://en.wikipedia.org/wiki/Floating-point_unit), and it is almost
-identical for x86 and x86_64 (except for the comparison
+identical for `x86` and `x86_64` (except for the comparison
 instructions, that have to be generated differently).  The
 program keeps track of the FPU stack (the FPU has a cyclic stack
 of 8 registers) and will automatically swap to and from the

2006/monge/index.html

@@ -553,7 +553,7 @@ numbers.</li>
 <li>There should be some way to switch from Mandelbrot to Julia with chosen
 parameter.</li>
 </ul>
-<h3 id="deobfuscation">Deobfuscation</h3>
+<h3 id="obfuscation">Obfuscation</h3>
 <p>Sure, I don’t want to deprive you of the pleasure of digging
 into the infernal mess created by my corrupted mind (writing
 this remark I noticed that I was ending sentences with ‘;’ instead
@@ -564,9 +564,9 @@ are different from the tricks used in most common IOCCC program
 of how all the program works to be worked out).</p>
 <p>This program is a formula parser that outputs machine code that
 calculates the formula and check the given conditions. The
-machine code targets the x87 stack based
+machine code targets the <code>x87</code> stack based
 <a href="https://en.wikipedia.org/wiki/Floating-point_unit">FPU</a>, and it is almost
-identical for x86 and x86_64 (except for the comparison
+identical for <code>x86</code> and <code>x86_64</code> (except for the comparison
 instructions, that have to be generated differently). The
 program keeps track of the FPU stack (the FPU has a cyclic stack
 of 8 registers) and will automatically swap to and from the

2006/toledo2/README.md

@@ -222,7 +222,7 @@ In Unix the min 0 on `stty` is required but circa 2001
 it was not required.
 
 
-### How it works (deobfuscation)
+### How it works (obfuscation)
 
 The `l` array contains the 64K memory; it is initialized with a boot image
 loaded from the `C` file. The [program

2006/toledo2/index.html

@@ -534,7 +534,7 @@ is not what is needed.</p>
 <p>On PC/DOS you need to add <code>ANSI.SYS</code> to <code>CONFIG.SYS</code>.</p>
 <p>In Unix the min 0 on <code>stty</code> is required but circa 2001
 it was not required.</p>
-<h3 id="how-it-works-deobfuscation">How it works (deobfuscation)</h3>
+<h3 id="how-it-works-obfuscation">How it works (obfuscation)</h3>
 <p>The <code>l</code> array contains the 64K memory; it is initialized with a boot image
 loaded from the <code>C</code> file. The <a href="https://en.wikipedia.org/wiki/Program_counter">program
 counter</a> is the <code>c</code> pointer and