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).

2018/index.html

@@ -407,14 +407,20 @@ remains functional in what it does.</p>
 <p>The <a href="burton1/index.html">Best one-liner - 2018/burton1</a>, at 109 characters, is a
 short and sweet implementation of a classic utility and a nod to a winning entry
 from 1986. Sometimes it takes 20 some years to do things the true IOCCC way.</p>
-<p>The color of the remarks text this year was inspired by one of the stars
-of the <a href="poikola/index.html">Most stellar - 2018/poikola</a>.</p>
 <p>The <a href="endoh2/index.html">Best use of python - 2018/endoh2</a> is not what you might think it is.
 It is something completely different.</p>
 <p>The <a href="ciura/index.html">Most likely to be awarded - 2018/ciura</a> has an amazing vocabulary!</p>
 <p>There are also nods to entries of the years <a href="../2000/bellard/index.html">2000/bellard</a>,
 <a href="../2015/yang/index.html">2015/yang</a>, …</p>
-<p>…We’ll stop spouting deobfuscation information now. Have fun exploring all the entries!</p>
+<p>…We’ll stop spouting spoilers now. Have fun exploring all the entries!</p>
+<h3 id="historical-note">Historical note:</h3>
+<p>In 2023-2024 the IOCCC website was drastically changed with the same look for
+every year and this changed the styling as well. But in 2018 different years had
+different stylesheets and we noted that:</p>
+<blockquote>
+<p>The color of the remarks text this year was inspired by one of the stars of
+the <a href="poikola/index.html">Most stellar - 2018/poikola</a>.</p>
+</blockquote>
 <h2 id="remarks-on-some-of-submissions-that-did-not-win">Remarks on some of submissions that did not win</h2>
 <p>The number of entries that would have made it into the final rounds
 would have been much higher had some people paid attention to rules 2