Correction: adds missing radio role allowance for img (#381)

* Correction: adds missing radio role allowance for img

closes #380.
As noted in #212, `role=radio` was meant to be allowed on an `img alt=foo`.  This corrects the mistake of that allowance not making it into the spec.

* update changelog

Author: scottaohara

index.html

@@ -1302,6 +1302,9 @@ <h2 id="docconformance">
                 <a href="#index-aria-menuitemradio">`menuitemradio`</a>,
                 <a href="#index-aria-option">`option`</a>,
                 <a href="#index-aria-progressbar">`progressbar`</a>,
+                <span class="proposed correction">
+                  <a href="#index-aria-radio">`radio`</a>,
+                </span>
                 <a href="#index-aria-scrollbar">`scrollbar`</a>,
                 <a href="#index-aria-separator">`separator`</a>,
                 <a href="#index-aria-slider">`slider`</a>,
@@ -4370,6 +4373,10 @@ <h2>Change log</h2>
       <h3>Substantive changes since the last published Recommendation</h3>
 
       <ul>
+        <li>
+          13-Dec-2021:
+          Allow `radio` role on <a href="#el-img">`img alt="some text"` element</a>.
+        </li>
         <li>
           07-Dec-2021:
           Allow only `none` and `presentation` roles for <a href="#el-wbr">`wbr` element</a>.