Edit CRM Word Template

Hi,

I want to merge CRM templates but rn:Microsoft-crm/document-template is missing in the XML Mapping pane. 

See below for the recreation steps and expected outcome

1. In Word > Click on the Developer Tab > Select XML Mapping Pane.

2. Expecting to see rn:Microsoft-crm/document-template but its missing 

I am working off a template downloaded from CRM. Am i missing any Add-ins in WORD ?

Reference - blog.sonomapartners.com/.../how-to-use-word-templates-in-crm-2016.html

Thanks,