Challenge 1: Updating a Table of Contents After a New Section — Solution Walkthrough

Setup: three Heading-1 sections, an automatic Table of Contents
already inserted, then a fourth Heading-1-styled section added
somewhere in the middle of the document.

What needs to happen:

Right-click the Table of Contents and choose "Update Field" (or
click into it and use References > Update Table), then select
"Update entire table" — NOT "Update page numbers only."

Why "Update entire table" specifically:

"Update page numbers only" assumes the SET of headings hasn't
changed — it just re-checks where each existing heading now sits on
the page. Here, an entirely new heading was added, which is a
genuinely new ENTRY the Table of Contents doesn't know about yet, not
just a page-number shift for the three it already lists. "Update page
numbers only" would correctly reflect that the original three
sections may have moved to different pages, but it would never add a
fourth ENTRY for the new section, since that option specifically
skips re-scanning the document's set of headings. Only "Update entire
table" fully re-scans the document for every Heading-styled paragraph
that currently exists, which is the only way the new fourth section
gets added as its own new listing.

Notes:
- This is exactly the distinction this chapter draws between the two
  update options: a page-number-only shift only needs the faster
  option, but anything involving added, removed, or retitled headings
  needs the full rebuild.