Introduce [parallel.simd.mask.unary]

Author: jaredhoberock

data_parallel_types.html

@@ -2669,6 +2669,20 @@ <h1><ins><code>simd_mask</code> subscript operators</ins></h1>
           </cxx-throws>
         </cxx-function>
       </cxx-section>
+
+      <cxx-section id="parallel.simd.mask.unary">
+        <h1><ins><code>simd_mask</code> unary operators</ins></h1>
+
+        <cxx-function>
+          <cxx-signature><ins>simd_mask operator!() const noexcept;</ins></cxx-signature>
+
+          <cxx-returns>
+          <ins>
+            The result of the element-wise appliation of <code>operator!</code>.
+          </ins>
+          </cxx-returns>
+        </cxx-function>
+      </cxx-section>
     </cxx-section>
   </cxx-section>
 </cxx-clause>