Fix validation for rules.html

Removed extraneous </p>.

next/rules.html

@@ -830,7 +830,6 @@ practices</a>.
 See also the <a href="https://www.markdownguide.org/basic-syntax">markdown syntax</a> guide
 and the <a href="https://spec.commonmark.org/current/">CommonMark Spec</a>.
 </p>
-</p>
 <p class="leftbar">
 The xz compressed tarball file <strong>MUST</strong> be less than or equal <strong>3999971</strong> octets in size.
 </p>