Revert "Add note on removal of mapping types in documentation"

This reverts commit 5a73074.

Author: ferdnyc

docs/source/examples/Widget List.ipynb

@@ -482,13 +482,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "There are several widgets that can be used to display single selection lists, and two that can be used to select multiple values.  All inherit from the same base class.  You can specify the **enumeration of selectable options by passing a list** (options are either (label, value) pairs, or simply values for which the labels are derived by calling `str`).\n",
-    "\n",
-    "<div class=\"alert alert-info\">\n",
-    "Changes in *ipywidgets 8*:\n",
-    "    \n",
-    "Selection widgets no longer accept a dictionary of options. Pass a list of key-value pairs instead.\n",
-    "</div>"
+    "There are several widgets that can be used to display single selection lists, and two that can be used to select multiple values.  All inherit from the same base class.  You can specify the **enumeration of selectable options by passing a list** (options are either (label, value) pairs, or simply values for which the labels are derived by calling `str`)."
    ]
   },
   {