Name the spread operator

Author: chx

language/types/array.xml

@@ -1162,7 +1162,8 @@ array(3) {
   <para>
    An array prefixed by <code>...</code> will be expanded in place during array definition.
    Only arrays and objects which implement <interfacename>Traversable</interfacename> can be expanded.
-   Array unpacking with <code>...</code> is available as of PHP 7.4.0.
+   Array unpacking with <code>...</code> is available as of PHP 7.4.0. This is also called
+   the spread operator.
   </para>
 
   <para>