Update in-page.md with more explicit directions for using {:toc} (#1551)

Fixes #1536.

docs/navigation/in-page.md

@@ -19,6 +19,27 @@ To support in-page navigation, you can generate a *Table of Contents* (TOC) with
 
 To generate a *Table of Contents* in a page, you use Kramdown's `{:toc}` method, immediately after the start of a list. This will automatically generate a list of anchor links to various sections of the page, based on headings and heading levels.
 
+{: .note }
+`{:toc}` can be used only once on each page.
+
+You **must** have a list immediately preceding the table of contents. The type of list determines the style of your table of contents.
+
+For an *ordered* table of contents, use the following markdown code:
+
+```md
+1. TOC
+{:toc}
+```
+
+The `{:toc}` line *must* follow the `1. TOC` line, which begins a list.
+
+For an *unordered* table of contents, instead use the following markdown code:
+
+```
+- TOC
+{:toc}
+```
+
 ## Omitting Heading from Table of Contents
 
 If you want to omit a particular heading from the TOC, follow it immediately by `{: .no_toc }` (possibly together with other CSS class names).
@@ -36,8 +57,6 @@ If you want to omit a particular heading from the TOC, follow it immediately by
 
 This example omits the top-level heading (`In-Page Navigation`) from the TOC, as well as the heading for the *Table of Contents* itself.
 
-To get an unordered list, replace `1. TOC` by `- TOC` in the above example.
-
 ## Collapsible Table of Contents (with `<details>` and `<summary>`)
 
 You can make the Table of Contents collapsible using the `<details>` and `<summary>` elements, as in the following example.
@@ -55,9 +74,6 @@ You can make the Table of Contents collapsible using the `<details>` and `<summa
 
 The attribute `open` (which expands the Table of Contents by default) and the styling (here with `text-delta`) are optional.
 
-{: .note }
-`{:toc}` can be used only once on each page.
-
 ## Back to Top {#back-to-top-doc}
 
 {: .warning }