improve rules and guidelines

We improved the rules language around `make clobber` to not insist,
but instead request actions to restore the state of the submission.

Updated `inc/rules.closed.hdr` and `inc/guidelines.closed.hdr` to clarify
the tentative nature of the rules and guidelines without implying
that they might be massively changed before the IOCCC re-opened.
The `next/rules.md` and `next/guidelines.md` have been updated to
include the `inc/rules.closed.hdr` and `inc/guidelines.closed.hdr`
content respectively.

The top level warning that the rules and guidelines are out of date
have been removed.

Performed `make rules guidelines` to update the HTML pages.

next/rules.html

@@ -425,12 +425,12 @@
 
 <!-- BEFORE: 1st line of markdown file: next/rules.md -->
 <!-- START: this line starts content from: inc/rules.closed.hdr -->
-<h1 id="warning-these-rules-are-out-of-date">WARNING: These rules are OUT OF DATE</h1>
-<p>These rules are a <strong>VERY TENTATIVE proposal</strong> for the next IOCCC
-and are <strong>VERY LIKELY</strong> to be updated before the next IOCCC.
-They are are provided as a <strong>VERY TENTATIVE</strong> hint at <strong>what
-MIGHT</strong> be used in the next IOCCC. In some cases they might
-even be a copy of the rules from the previous IOCCC.</p>
+<h1 id="the-ioccc-is-closed">The IOCCC is closed</h1>
+<p>The IOCCC is <strong>NOT</strong> accepting new submissions at this time. See the
+<a href="../years.html">IOCCC winning entries page</a> for the entries that have won the
+IOCCC in the past.</p>
+<p>These rules are a <strong>TENTATIVE proposal</strong> for the next IOCCC
+and are <strong>likely be to be updated</strong> before the next IOCCC.</p>
 <p>See our
 FAQ on “<a href="../faq.html#feedback">rules, guidelines, tools feedback</a>”
 as well as our
@@ -438,10 +438,6 @@ FAQ on “<a href="../faq.html#question">about asking questions</a>”
 about these rules. You might also find the
 FAQ in general useful, especially the
 <a href="../faq.html#submit">FAQ section “How to enter: the bare minimum you need to know”</a>.</p>
-<h1 id="the-ioccc-is-closed">The IOCCC is closed</h1>
-<p>The IOCCC is <strong>NOT</strong> accepting new submissions at this time. See the
-<a href="../years.html">IOCCC winning entries page</a> for the entries that have won the
-IOCCC in the past.</p>
 <p>Watch both <a href="../status.html">the IOCCC status page</a> and the
 <a href="https://fosstodon.org/@ioccc"><span class="citation" data-cites="IOCCC">@IOCCC</span> mastodon feed</a> for information about
 future IOCCC openings.</p>
@@ -1117,9 +1113,9 @@ C source file must be called <code>prog.c</code>.</p>
 <code>${CPP}</code>.</p>
 <p>Do <strong>NOT</strong> assume that <code>.</code> (the current directory) is in the <code>$PATH</code>.</p>
 <p class="leftbar">
-When <code>make clobber</code> is invoked, your submission <strong>MUST</strong> be restored
+When <code>make clobber</code> is invoked, we request that submission be restored
 to its original submission state. For example, any temporary files
-created during the build process, or during execution <strong>MUST</strong> be
+created during the build process, or during execution should be
 removed by the <code>clobber</code> rule.
 </p>
 <p class="leftbar">