Add first movement to docs

[Rosefield]

This was added last minute to the release and I forgot to update the docs with it. This feature is currently in the preview build.

[opbld33]

Docs Build status updates of commit bb30f68:

✅ Validation status: passed

File	Status	Preview URL	Details
TerminalDocs/panes.md	✅Succeeded	View

For more details, please refer to the build report.

Note: Broken links written as relative paths are included in the above build report. For broken links written as absolute paths or external URLs, see the broken link report.

For any questions, please:

• Try searching the docs.microsoft.com contributor guides
• Post your question in the Docs support channel

[Rosefield]

@zadjii-msft not sure what the process is for updating the docs when something is incorrect in a live build, instead of just new features so I'm tagging you.