Ts file snippet is not rendering

[LowBP]

Steps to reproduce the behavior:

1. Ember install ember-cli-typescript --save
2. Create a route docs/button
3. In docs/button/controller.ts

  // BEGIN-SNIPPET docs-button.ts
    @action  
       onClick(){
      }
  // END-SNIPPET

4. In docs/button/template.hbs {{demo.snippet name='docs-button.ts'}}

Version details

 "ember-cli": "~3.8.1",
 "ember-source": "~3.8.0",
 "ember-cli-addon-docs": "^0.6.7",
 "ember-cli-typescript": "^2.0.0",

[dfreeman]

Looks like 'ts' should be added to the default snippet extensions array