Replace straggler WAI/WCAG21 links to WAI/WCAG22 (#4564)

Closes #3635

---------

Co-authored-by: Mike Gower <mikegower@gmail.com>

Author: patrickhlauke

techniques/html/H4.html

@@ -6,7 +6,7 @@
       <p>HTML and XHTML</p>
    </section><section id="description"><h2>Description</h2>
       <p>The objective of this technique is to provide a logical tab order when the default tab
-            order does not suffice. Often, <a href="https://www.w3.org/WAI/WCAG21/Techniques/general/G59">placing the
+            order does not suffice. Often, <a href="https://www.w3.org/WAI/WCAG22/Techniques/general/G59">placing the
               interactive elements in an order that follows sequences and relationships within the
               content</a> is sufficient and this technique is not necessary. It can be very easy
             to introduce usability bugs when setting the tab order explicitly.</p>

techniques/html/H70.html

@@ -21,8 +21,8 @@
       <p>This technique is appropriate when framesets are already used to organize the content
             of the page; other techniques are preferred for pages that are not already using
             framesets, because many people using assistive technology have trouble with frames . An
-            advisory technique about using noframes is available in <a href="https://www.w3.org/WAI/WCAG21/Understanding/non-text-content">Success Criterion 1.1.1</a>. </p>
-      <p>In HTML5 the <code>frame</code> element is marked as obsolete.</p>
+            advisory technique about using noframes is available in <a href="https://www.w3.org/WAI/WCAG22/Understanding/non-text-content">Success Criterion 1.1.1</a>. </p>
+      <p>In HTML5 the <code class="el">frame</code> element is marked as obsolete.</p>
    </section><section id="examples"><h2>Examples</h2>
       <section class="example">
 

techniques/html/H73.html

@@ -25,9 +25,9 @@
                elements and to conform to the coding practice of separating presentation from content.
                However, if a layout table is used, then the <code>summary</code> attribute is not used or
                is null. The purpose of a layout table is simply to control the placement of content;
-               the table itself is “transparent" to the user. A <code>summary</code> would “break" this
-               transparency by calling attention to the table. A null <code>summary</code>
-                 (<code>summary</code>="") on layout tables is acceptable. See <a href="https://www.w3.org/WAI/WCAG21/Techniques/failures/F46">F46</a> for details.</p>
+               the table itself is “transparent" to the user. A <code class="att">summary</code> would “break" this
+               transparency by calling attention to the table. A null <code class="att">summary</code>
+                 (<code class="att">summary</code>="") on layout tables is acceptable. See <a href="https://www.w3.org/WAI/WCAG22/Techniques/failures/F46">F46</a> for details.</p>
       </div>
    </section><section id="examples"><h2>Examples</h2>
       <section class="example">

techniques/html/H74.html

@@ -62,7 +62,7 @@ <h2>Resources</h2>
                   <a href="https://html.spec.whatwg.org/multipage/syntax.html#the-doctype">HTML - The <code>doctype</code></a>.
                </li>
                <li>
-                  <a href="https://www.w3.org/WAI/WCAG21/Techniques/general/G134">Validating web pages</a>.
+                  <a href="https://www.w3.org/WAI/WCAG22/Techniques/general/G134">Validating web pages</a>.
                </li>
                <li>
                   <a href="https://validator.w3.org/nu/">The W3C's Nu HTML Checker</a>.

techniques/html/H75.html

@@ -75,7 +75,7 @@ <h3></h3>
                     Entities</a> in Extensible Markup Language (XML) 1.1, W3C Recommendation 04
                   February 2004.</li>
          </ul>
-         <p> For other resources, see <a href="https://www.w3.org/WAI/WCAG21/Techniques/general/G134">Validating web
+         <p> For other resources, see <a href="https://www.w3.org/WAI/WCAG22/Techniques/general/G134">Validating web
               pages</a>. </p>
 
    </section></body></html>

techniques/html/H88.html

@@ -56,7 +56,7 @@ <h2>Related Techniques</h2>
       <li><a href="../html/H75">H75</a></li>
    </ul></section><section id="resources"><h2>Resources</h2>
 
-         <p>Refer to the resources section of <a href="https://www.w3.org/WAI/WCAG21/Techniques/general/G134">Validating web
+         <p>Refer to the resources section of <a href="https://www.w3.org/WAI/WCAG22/Techniques/general/G134">Validating web
                         pages</a>. </p>
 
    </section></body></html>