BNumbers for Docs
OpenDevEd has been streaming our Google Docs / Sheets / Slides workflows for many years, going back almost until the initial launch of the apps script. For more details about all our Add-ons, see Our Tools.
BNumbers for Docs provides a number of utility functions for Google Docs. In particular, it offers various styles of heading numbering. Where headings are inserted into the Google Doc using the native linking function, numbers used in the links are updated.
For details, visit our GitHub repository here google-apps-script/repositories and select BNumbers for Docs.