Add title to mushroom proportions notebook

https://github.com/microsoft/Data-Science-For-Beginners/blob/main/translations/ja/3-Data-Visualization/11-visualization-proportions/notebook.ipynb
#PingMSFTDocs

Author: hyoshioka0128

translations/ja/3-Data-Visualization/11-visualization-proportions/notebook.ipynb

@@ -2,7 +2,9 @@
  "cells": [
   {
    "cell_type": "markdown",
-   "source": [],
+   "source":  [
+    "# 🍄 Mushroom Proportions"
+   ],
    "metadata": {}
   },
   {
@@ -27,4 +29,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 2
-}
+}