[all hosts] (Preview APIs) Add intro for OfficeScript namespace table (#397)

* [all hosts] (Preview APIs) Add intro for OfficeScript namespace table

* Update phrasing

* Update phrasing

* Update docs/docs-ref-autogen/preview-apis.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update docs/docs-ref-autogen/preview-apis.md

Co-authored-by: Alex Jerabek <38896772+AlexJerabek@users.noreply.github.com>

* Update docs/docs-ref-autogen/preview-apis.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Alex Jerabek <38896772+AlexJerabek@users.noreply.github.com>

Author: 3 people

docs/docs-ref-autogen/preview-apis.md

@@ -2,7 +2,7 @@
 title: Office Scripts preview APIs
 description: Details about upcoming Office Scripts APIs.
 ms.topic: whats-new
-ms.date: 09/08/2025
+ms.date: 09/12/2025
 ---
 
 # Office Scripts preview APIs
@@ -12,15 +12,17 @@ New Office Scripts APIs are first introduced in "preview", and then later releas
 > [!IMPORTANT]
 > Preview APIs are subject to change and are not intended for use in a production environment. We recommend that you try them out in test and development environments only. Do not use preview APIs in a production environment or within business-critical documents.
 
-The following table provides a concise summary of the APIs, while the subsequent [API list](#api-list) table gives a detailed list.
+The following table provides a concise summary of the APIs, while the subsequent [API list](#api-list) section gives a detailed list.
 
 | Feature area | Description | Relevant objects |
 |:--- |:--- |:--- |
 | Save and email a PDF | Save a worksheet as a PDF and email it to yourself or your team. For a sample, see [Save a worksheet and email it as a PDF](/office/dev/scripts/resources/samples/save-as-pdf-email-as-pdf). | [EmailAttachment](/javascript/api/office-scripts/officescript/officescript.emailattachment), [MailProperties](/javascript/api/office-scripts/officescript/officescript.mailproperties) |
 
 ## API list
 
-The following table lists the Office Scripts APIs currently in preview.
+Office Scripts APIs use two namespaces: `OfficeScript` for APIs that are not connected to an Excel workbook, and `ExcelScript` for APIs that work with Excel workbooks. Currently, the only preview APIs are in the `OfficeScript` namespace. The following section lists those APIs.
+
+### OfficeScript namespace
 
 [!INCLUDE[API table](../includes/officescript-preview.md)]