To automatically create a clickable Table of Contents (TOC) in Google Docs:
1) First, you must go through your document and make the headings into “Heading 1’s”:
1) Click and drag over the chapter name, such as “Chapter 1.”
2) Click on where it says, “Normal text” at the top of the Google Docs window.
3) Click on Heading 1, then on Apply ‘Heading 1.’
4) Repeat steps 1 through 4 for every heading that you want to be in the TOC. (Heading 1 would be for the chapter heading. Heading 2 would be for a subsection heading, and so on.)
2) Click where you want the TOC to go in your document. This is usually at the top of your document.
3) Click on Insert at the top of the Google Docs window, then click on Table of Contents (at the very bottom of the menu).
4) Click on the picture of the format you want, such as a TOC with page numbers, or with no page numbers.
5) Later, when you add another chapter, you can make it into a Heading 1, then right-click on the TOC itself, then click on Update toc. (You can also click on Delete toc here if you want to just get rid of the TOC.)