Setting Links inside a page using the WYSIWYG Editor at design time is brokn #2278

Describe the bug
When you edit a page and want to set links to different heading of that page the "Insert/Edit Link"-functionality of the editor offers you the headings available on the page. These links don't work after saving.

Steps To Reproduce
Steps to reproduce the behavior:

1. Create a new page
2. Add content and heading
3. Mark a word and press on Insert/Edit Link
4. Click in the URL text field and choose a heading
   
   

5 . Klick ok and save the page
6. After clicking on the link on the page nothing happens. The anchor set for the text doesn't exist

Expected behavior
The link should link to the correct heading.

Your Configuration (please complete the following information):

• Exact BookStack Version (Found in settings): 0.30
• Hosting Method (Nginx/Apache/Docker): docker (Linuxserver.io)