docs(errors): fix headings hierarchy for first error

docs/advices/index.html

@@ -821,7 +821,7 @@ <h3 id="test">Test</h3>
 </svg>
       </a>
     </p>
-    <p>® 2014 —&nbsp;2020 <strong>Gaël Poupard</strong></p>
+    <p>® 2014 —&nbsp;2022 <strong>Gaël Poupard</strong></p>
     <p>This project is distributed under license <a href="https://opensource.org/licenses/MIT" title="The MIT licence">MIT</a> and <a href="https://creativecommons.org/licenses/by/3.0/fr/" hreflang="fr" title="Explications de la licence">CC BY 3.0 FR</a>. <a class="end" href="#top">Back to top</a></p>
   </div>
 </footer>

docs/api/index.html

@@ -1681,7 +1681,7 @@ <h5 id="interactive-elements-references">References</h5>
 </svg>
       </a>
     </p>
-    <p>® 2014 —&nbsp;2020 <strong>Gaël Poupard</strong></p>
+    <p>® 2014 —&nbsp;2022 <strong>Gaël Poupard</strong></p>
     <p>This project is distributed under license <a href="https://opensource.org/licenses/MIT" title="The MIT licence">MIT</a> and <a href="https://creativecommons.org/licenses/by/3.0/fr/" hreflang="fr" title="Explications de la licence">CC BY 3.0 FR</a>. <a class="end" href="#top">Back to top</a></p>
   </div>
 </footer>

docs/errors/index.html

@@ -365,20 +365,20 @@ <h1>Errors</h1>
 
         <article>
           <h2 id="attribute-whitespace">Attribute should not contain whitespace</h2>
-          <h2 id="description">Description</h2>
+          <h3 id="description">Description</h3>
 <p>Some HTML attributes should not contain any whitespace —namely <code>[id]</code>, <code>[lang]</code> and <code>map[name]</code>.</p>
-<h2 id="reference">Reference</h2>
+<h3 id="reference">Reference</h3>
 <ul>
 <li><a href="https://html.spec.whatwg.org/#the-id-attribute">https://html.spec.whatwg.org/#the-id-attribute</a></li>
 <li><a href="https://html.spec.whatwg.org/#the-map-element">https://html.spec.whatwg.org/#the-map-element</a></li>
 <li><a href="https://tools.ietf.org/html/bcp47#section-2.1.1">https://tools.ietf.org/html/bcp47#section-2.1.1</a></li>
 </ul>
-<h2 id="selector">Selector</h2>
+<h3 id="selector">Selector</h3>
 <pre><code class="css_example language-css_example">[id*=" "],
 [lang*=" "],
 map[name*=" "]
 </code></pre>
-<h2 id="test">Test</h2>
+<h3 id="test">Test</h3>
 <pre><code class="html_example language-html_example">&lt;p id="my id"&gt;This is my beautiful element with an ID&lt;/p&gt;
 </code></pre>
         </article>
@@ -1531,7 +1531,7 @@ <h3 id="test">Test</h3>
 </svg>
       </a>
     </p>
-    <p>® 2014 —&nbsp;2020 <strong>Gaël Poupard</strong></p>
+    <p>® 2014 —&nbsp;2022 <strong>Gaël Poupard</strong></p>
     <p>This project is distributed under license <a href="https://opensource.org/licenses/MIT" title="The MIT licence">MIT</a> and <a href="https://creativecommons.org/licenses/by/3.0/fr/" hreflang="fr" title="Explications de la licence">CC BY 3.0 FR</a>. <a class="end" href="#top">Back to top</a></p>
   </div>
 </footer>

docs/index.html

@@ -169,7 +169,7 @@ <h2>Contribution</h2>
 </svg>
       </a>
     </p>
-    <p>® 2014 —&nbsp;2020 <strong>Gaël Poupard</strong></p>
+    <p>® 2014 —&nbsp;2022 <strong>Gaël Poupard</strong></p>
     <p>This project is distributed under license <a href="https://opensource.org/licenses/MIT" title="The MIT licence">MIT</a> and <a href="https://creativecommons.org/licenses/by/3.0/fr/" hreflang="fr" title="Explications de la licence">CC BY 3.0 FR</a>. <a class="end" href="#top">Back to top</a></p>
   </div>
 </footer>

docs/obsoletes/index.html

@@ -323,7 +323,7 @@ <h3 id="test">Test</h3>
 </svg>
       </a>
     </p>
-    <p>® 2014 —&nbsp;2020 <strong>Gaël Poupard</strong></p>
+    <p>® 2014 —&nbsp;2022 <strong>Gaël Poupard</strong></p>
     <p>This project is distributed under license <a href="https://opensource.org/licenses/MIT" title="The MIT licence">MIT</a> and <a href="https://creativecommons.org/licenses/by/3.0/fr/" hreflang="fr" title="Explications de la licence">CC BY 3.0 FR</a>. <a class="end" href="#top">Back to top</a></p>
   </div>
 </footer>

docs/warnings/index.html

@@ -1576,7 +1576,7 @@ <h3 id="test">Test</h3>
 </svg>
       </a>
     </p>
-    <p>® 2014 —&nbsp;2020 <strong>Gaël Poupard</strong></p>
+    <p>® 2014 —&nbsp;2022 <strong>Gaël Poupard</strong></p>
     <p>This project is distributed under license <a href="https://opensource.org/licenses/MIT" title="The MIT licence">MIT</a> and <a href="https://creativecommons.org/licenses/by/3.0/fr/" hreflang="fr" title="Explications de la licence">CC BY 3.0 FR</a>. <a class="end" href="#top">Back to top</a></p>
   </div>
 </footer>

docs/webextension/index.html

@@ -290,7 +290,7 @@ <h3 id="test">Test</h3>
 </svg>
       </a>
     </p>
-    <p>® 2014 —&nbsp;2020 <strong>Gaël Poupard</strong></p>
+    <p>® 2014 —&nbsp;2022 <strong>Gaël Poupard</strong></p>
     <p>This project is distributed under license <a href="https://opensource.org/licenses/MIT" title="The MIT licence">MIT</a> and <a href="https://creativecommons.org/licenses/by/3.0/fr/" hreflang="fr" title="Explications de la licence">CC BY 3.0 FR</a>. <a class="end" href="#top">Back to top</a></p>
   </div>
 </footer>

sass/themes/_error.scss

@@ -7,22 +7,22 @@ name: attribute-whitespace
 category: Errors
 ---
 
-## Description
+### Description
 Some HTML attributes should not contain any whitespace —namely `[id]`, `[lang]` and `map[name]`.
 
-## Reference
+### Reference
 * <https://html.spec.whatwg.org/#the-id-attribute>
 * <https://html.spec.whatwg.org/#the-map-element>
 * <https://tools.ietf.org/html/bcp47#section-2.1.1>
 
-## Selector
+### Selector
 ```css_example
 [id*=" "],
 [lang*=" "],
 map[name*=" "]
 ```
 
-## Test
+### Test
 ```html_example
 <p id="my id">This is my beautiful element with an ID</p>
 ```