How do I add anchor links to articles?

Yayy! I solved this by myself 😀 Here's instructions if someone else is wondering the same:

First: Helpcenter doesn't need to be published to see collections so called ID's. The ID of each collection can be checked from the workspace (Article-view) directly. Just navigate to Articles -> Help Center and click collection name -> the ID can be checked from the page URL.

The link which leads to some certain section in the collage contains following parts. I'll use https://www.intercom.com/help/en/collections/2091449-sending-messages-and-building-smart-campaigns#sending-messages-with-intercom as an example URL.

1. Start with the help center URL / domain. You can check this from the Help Center Settings. In that example above the URL is https://www.intercom.com/help/
2. After the URL add the language of the collection, for example en/
3. Then add collections/collection ID-collection name#section name, like /collections/2091449-sending-messages-and-building-smart-campaigns#sending-messages-with-intercom. In that example "Sending messages and building smart campaigns" is the name of the collection and "Sending messages with intercom" is the section's name. Remember to use key - to separate the words.
4. The URL which leads to certain section in the collection is now ready If the helpcenter is already published you can easily check is the URL working