In the "Arranging Chapters in the Navigator" section of the LO Help (found by searching for "arranging;headings"), it says "To undock the Navigator, double-click its frame." It should say "To undock the Navigator, double-click its frame while holding the Ctrl key." The "Navigator;docking and resizing" search leads to "Docking and Resizing Windows" which does have the correct instructions. Maybe the above instructions should be replaced by a link to that instead?
Good catch, thank you! Patch submitted to Gerrit: https://gerrit.libreoffice.org/#/c/19838/
Stanislav Horacek committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/help/commit/?id=e3edc535120b598fe44f7b9500d6433eb611ac61 tdf#95626 add holding Ctrl key to undocking Navigator