How to add intellisense to packages.config (nuget packages) without losing all the setting when adding more packages

Question

I updated the packages element in packages.config as follows:

<packages xmlns="urn:packages">

Also added a packages.xsd:

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified"
      targetNamespace="urn:packages" xmlns="urn:packages">
  <xs:element name="packages">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="package" maxOccurs="unbounded">
          <xs:complexType>
            <xs:attribute name="id" type="xs:string" use="required" />
            <xs:attribute name="version" type="xs:string" use="required" />
            <xs:attribute name="targetFramework" type="xs:string" use="optional" />
            <xs:attribute name="allowedVersions" type="xs:string" use="optional" />
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

Now, every time I add packages the packages.config resets with just the new package...

I'm using Visual Studio 2013 with Nuget.Core.2.8.3

Any idea how to get it working with the intellisense?