Fortunately, there are freely available table of contents templates that can be used in Google Docs. Once you have opened the template you can begin customizing the template to suit your own needs.

The following example uses ODS to display the output in HTML with a table of contents. The data is the population of the United States in millions recorded at ten year intervals starting in 1790 and ...

Google Docs is adding more customization options for table of contents, as well as better formatting options for tables ...

You can create a table of contents in Microsoft Word where every chapter title links to the appropriate chapter. Then you can keep these links live when you convert the document to a PDF.