Feature: Add a document section

In order to change page layout mid-document

As a developer using python-docx

I need a way to add a new section to a document

Scenario: Add a landscape section to a portrait document

Given a single-section document having portrait layout

When I add an even-page section to the document

And I change the new section layout to landscape

Then the document has two sections

And the first section is portrait

And the second section is landscape