How to include task links in twig node template
https://www.drupal.org/docs/8/api/menu-api/providing-module-defined-contextual-links
The manual says: 

Contextual links are stored in title_suffix. This variable needs to be printed in the html.twig file, such as in this example from block.links.contextual.yml.

&lt;div{{ attributes }}&gt;
  {{ title_suffix }}
  ...
&lt;/div&gt;