updating content in option mapping table and accName steps

Author: scottaohara

html-aam/index.html

@@ -11732,7 +11732,8 @@ <h4 id="att-label">`label`</h4>
             <tr>
               <th>Element(s)</th>
               <td>
-                <a data-cite="html/form-elements.html#attr-optgroup-label">`optgroup`</a>; <a data-cite="html/form-elements.html#attr-option-label">`option`</a>;
+                <a data-cite="html/form-elements.html#attr-optgroup-label">`optgroup`</a>; 
+                <a data-cite="html/form-elements.html#attr-option-label">`option`</a>;
                 <a data-cite="html/media.html#attr-track-label">`track`</a>
               </td>
             </tr>
@@ -11753,12 +11754,7 @@ <h4 id="att-label">`label`</h4>
             <tr>
               <th><a href="https://msdn.microsoft.com/en-us/library/ms726297%28v=VS.85%29.aspx">UIA</a></th>
               <td>
-                The target element of the `label` attribute has a `LabeledBy` property pointing to the element with the `label` attribute. Participates in
-                <a href="#accname-computation">name computation.</a>
-                <!--
-                  This UIA definition doesn't seem right.  May replace with:
-                  <div class="name">Associates the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a></div>
-                -->  
+                <div class="name">Associates the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a></div>  
               </td>
             </tr>
             <tr>
@@ -11774,7 +11770,13 @@ <h4 id="att-label">`label`</h4>
             <tr>
               <th>Comments</th>
               <td>
-               <!-- 
+                <div class="note">
+                  <p>The `label` attribute behaves differently when declared on an `optgroup` element compared to an `option` element.</p>
+                  <p>If the `label` attribute is declared on an `option` element, its value will become the rendered label of the `option` element, even if the `option` element has child elements.</p>
+                  <p>If the `label` attribute is declared on an `optgroup` element that is a descendant of a customizable `select` element, and that `optgroup` has a child `legend` element, then the `legend` element takes priority. The `label` attribute's value will not be rendered or exposed to the accessibility tree as the name of the `opgroup`.
+                </div>
+
+                 <!-- 
                 FOR FUTURE PR https://github.com/w3c/html-aam/issues/568 :
                 The `label` attribute can also participate in the <a data-cite="accname-1.2/#dfn-accessible-description">accessible descriptions</a> of
                 an `option`, if the `option` is a child of a `datalist`. 
@@ -16229,7 +16231,7 @@ <h4>`option` Element Accessible Name Computation</h4>
               If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty: use the value of the `option` element's `label` attribute.
             </li>
             <li>
-              If no `label` attribute is specified, or its value is the empty string: use the <a data-cite="accname-1.2/#mapping_additional_nd_te">text equivalent computation</a> of the `option` element's subtree.
+              If no `label` attribute is specified: use the <a data-cite="accname-1.2/#mapping_additional_nd_te">text equivalent computation</a> of the `option` element's subtree.
             </li>
             <li>
               Otherwise: