Add the word 'package' to the --without-ensurepip explanation

Because it can be misleading for some users.

was r11567.

chapter05/python.xml

@@ -61,7 +61,7 @@
       <varlistentry>
         <term><parameter>--without-ensurepip</parameter></term>
         <listitem>
-          <para>该选项禁止构建 Python 安装器，它在当前阶段没有必要。</para>
+          <para>该选项禁止构建 Python 软件包安装器，它在当前阶段没有必要。</para>
         </listitem>
       </varlistentry>