For each module listed at /admin/modules, Drupal now provides a link to the project page on Drupal.org.
This new link is titled "Project page", and is presented next to the existing Help, Permissions and Configure links.

The link will be automatically added for modules downloaded from Drupal.org
The link is constructed using the project key in a module's info.yml file, this key is automatically added by Drupal.org's packaging system.
Therefor, new and existing modules downloaded from Drupal.org do not need to make any changes for this link to appear.
The "Project page" link will not be added for custom modules.
Changes to modules-details Twig template
To support this new link the system-modules-details.html.twig Twig template has been updated to include the project_page link.
If you are a theme developer and you have overridden this template, you should update your template to include this new link.
<div class="links">
- {% for link_type in ['help', 'permissions', 'configure'] %}
+ {% for link_type in ['help', 'permissions', 'configure', 'project_page'] %}
{{ module.links[link_type] }}
{% endfor %}
</div>