latex template fix to allow flextable to render tables

[kelliemac]

Description

Currently, attempting to use flextable for PDF output results in an error due to a command missing in the template.tex file. This fix resolves that issue, and flextable can now be used to generate tables in both Word and PDF report documents.

Checklist

• [ ] This PR includes unit tests
• [ ] This PR establishes a new function or updates parameters in an existing function
  • [ ] The roxygen skeleton for this function has been updated using devtools::document
• [x] I have updated NEWS.md to describe the proposed changes

[slager]

Sorry about that, I pushed a bad commit and then removed it. Looks good!