Change contact email template type text to html in magento

How do change contact email template type text to html

Go to app/code/core/Mage/Contacts/etc/config.xml

<email>
               <contacts_email_email_template translate="label" module="contacts">
                   <label>Contact Form</label>
                   <file>contact_form.html</file>
                   <type>text</type>
               </contacts_email_email_template>
           </email>

Change to this

<email>
               <contacts_email_email_template translate="label" module="contacts">
                   <label>Contact Form</label>
                   <file>contact_form.html</file>
                   <type>html</type>
               </contacts_email_email_template>
           </email>