Marks a section as non-normative. ReSpec automatically prepends the standard "This section is non-normative." paragraph.

<section class="informative">
  <h2>Background and Motivation</h2>
  <p>This section explains the history behind this feature…</p>
</section>

• Use for introductions, use cases, examples, and explanatory material that readers are not required to implement
• The "This section is non-normative." prefix is added automatically — don't add it manually
• Combine with class="appendix" for informative appendices: class="appendix informative"
• Note that ednote sections are also non-normative and are typically stripped before publication