Remove the _model variable from the group label template example

Author: m1r0

documentation/3-complex-field/5-setup-methods.md

@@ -74,10 +74,6 @@ Example usage:
 ))
 ->set_header_template('
  <# if (name && drivers_license_id) { #>
- <# if (picture) { #>
- <img src="{{ _models.picture.get("url") }}" width="18" height="18">
- <# } #>
-
  Driver: {{ name }}, {{ drivers_license_id }}
  <# } #>
 ')