Addition: allow role=separator on button elements (#489)

closes #488 

allows role=separator on elements exposed as a button.  

any other author requirements for appropriately setting that up / ensuring the correct information is communicated would still need to be evaluated, but separate from whether the role is allowed or not.

* Addition: allow role=separator on button elements
* update changelog

Author: scottaohara

index.html

@@ -64,9 +64,13 @@
         the following substantive additions and/or corrections have been proposed:
       </p>
       <ul>
+        <li>
+          <a href="https://github.com/w3c/html-aria/pull/489">4 October 2023 - Addition:</a>
+          Update the button element and input type=button,image,reset,submit elements to allow the `separator` role.
+        </li>
         <li>
           <a href="https://github.com/w3c/html-aria/pull/453">3 October 2023 - Correction:</a>
-          Update the <a href="#el-img">`img`</a> element allowances to be based on whether the element is named, or not.
+          Update the <a href="#el-img">`img`</a> element allowances to be based on if the element has an accessible name or not.
         </li>
         <li>
           <a href="https://github.com/w3c/html-aria/pull/462">21 August 2023 - Addition:</a>
@@ -885,7 +889,9 @@ <h2 id="docconformance">
                 <a href="#index-aria-menuitemradio">`menuitemradio`</a>,
                 <a href="#index-aria-option">`option`</a>,
                 <a href="#index-aria-radio">`radio`</a>,
-                <span class="proposed addition"><a href="#index-aria-slider">`slider`</a></span>,
+                <span class="proposed addition">
+                  <a href="#index-aria-separator">`separator`</a>,
+                  <a href="#index-aria-slider">`slider`</a></span>,
                 <a href="#index-aria-switch">`switch`</a>,
                 <a href="#index-aria-tab">`tab`</a>,
                 or <span class="proposed addition"><a href="#index-aria-treeitem">`treeitem`</a></span>.
@@ -1669,7 +1675,9 @@ <h2 id="docconformance">
                 <a href="#index-aria-menuitemradio">`menuitemradio`</a>,
                 <a href="#index-aria-option">`option`</a>,
                 <a href="#index-aria-radio">`radio`</a>,
-                <span class="proposed addition"><a href="#index-aria-slider">`slider`</a>,</span>
+                <span class="proposed addition">
+                  <a href="#index-aria-separator">`separator`</a>,
+                  <a href="#index-aria-slider">`slider`</a>,</span>
                 <a href="#index-aria-switch">`switch`</a>,
                 <a href="#index-aria-tab">`tab`</a>,
                 or <span class="addition proposed"><a href="#index-aria-treeitem">`treeitem`</a></span>. 
@@ -1828,6 +1836,7 @@ <h2 id="docconformance">
                   <a href="#index-aria-menuitemradio">`menuitemradio`</a>,
                   <a href="#index-aria-option">`option`</a>,
                   <a href="#index-aria-radio">`radio`</a>,
+                  <a href="#index-aria-separator">`separator`</a>,
                   <a href="#index-aria-slider">`slider`</a>,
                   <a href="#index-aria-switch">`switch`</a>,
                   <a href="#index-aria-tab">`tab`</a>
@@ -1961,6 +1970,7 @@ <h2 id="docconformance">
                   <a href="#index-aria-menuitemradio">`menuitemradio`</a>,
                   <a href="#index-aria-option">`option`</a>,
                   <a href="#index-aria-radio">`radio`</a>,
+                  <a href="#index-aria-separator">`separator`</a>,
                   <a href="#index-aria-slider">`slider`</a>,
                   <a href="#index-aria-switch">`switch`</a>,
                   <a href="#index-aria-tab">`tab`</a>
@@ -2015,6 +2025,7 @@ <h2 id="docconformance">
                   <a href="#index-aria-menuitemradio">`menuitemradio`</a>,
                   <a href="#index-aria-option">`option`</a>,
                   <a href="#index-aria-radio">`radio`</a>,
+                  <a href="#index-aria-separator">`separator`</a>,
                   <a href="#index-aria-slider">`slider`</a>,
                   <a href="#index-aria-switch">`switch`</a>,
                   <a href="#index-aria-tab">`tab`</a>