Updated possible values for display errors INI configurations

[Narkunan]

Fix issue #2525

[Narkunan]

@lacatoire Updated PR please review it let me know if any changes needed

[Narkunan]

@lacatoire Done made all suggested changes

[jordikroon]

This block is redundant with the line below. Nevertheless given the structure I would remove this completely.

[jordikroon]

This should go above the note.

[jordikroon]

Could you take inspiration from syslog.filter? In other words it is using <itemizedlist>.

<varlistentry xml:id="ini.display-errors">
 <term>
  <parameter>display_errors</parameter>
  <type>string</type>
 </term>
 <listitem>
  <para>
   This determines whether errors should be printed to the screen
   as part of the output or if they should be hidden from the user.
   <itemizedlist>
    <listitem>
     <simpara>
      <literal>Off</literal> - do not display any errors.
     </simpara>
    </listitem>
    <listitem>
     <simpara>
      <literal>On</literal> or <literal>stdout</literal> - display errors to <literal>stdout</literal>. This is the default.
     </simpara>
    </listitem>
    <listitem>
     <simpara>
      <literal>stderr</literal> - display errors to <literal>stderr</literal>. Only effective for the <literal>CLI,</literal><literal>phpdbg</literal>and<literal>CGI</literal> SAPIs.
     </simpara>
    </listitem>
   </itemizedlist>
  </para>
 </listitem>
</varlistentry>

[jordikroon]

Sorry this took so long to review. Overall looks good, just some structural/style comments to make it more in consistent.