docs(react-persona): Adding migration guide

[sopranopillow]

This PR adds the migrations guide for v8's Persona to v9's Persona.

Related Issue(s)

Fixes #24956

[fabricteam]

📊 Bundle size report

Unchanged fixtures

Package & Exports	Size (minified/GZIP)
react-components react-components: Accordion, Button, FluentProvider, Image, Menu, Popover	189.156 kB 52.385 kB
react-components react-components: FluentProvider & webLightTheme	33.4 kB 11.008 kB
react-portal-compat PortalCompatProvider	5.857 kB 1.978 kB

_{🤖 This report was generated against cbf3f6457b933224b76fc281cfa9e827085055d1}

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 80922fa:

Sandbox	Source
@fluentui/react 8 starter	Configuration
@fluentui/react-components 9 starter	Configuration

[size-auditor]

Asset size changes

Size Auditor did not detect a change in bundle size for any component!

Baseline commit: cbf3f6457b933224b76fc281cfa9e827085055d1 (build)

[fabricteam]

Perf Analysis (@fluentui/react-components)

No significant results to display.

All results

Scenario	Render type	Master Ticks	PR Ticks	Iterations	Status
Avatar	mount	1278	1296	5000
Button	mount	921	923	5000
FluentProvider	mount	1510	1488	5000
FluentProviderWithTheme	mount	576	580	10
FluentProviderWithTheme	virtual-rerender	543	541	10
FluentProviderWithTheme	virtual-rerender-with-unmount	573	595	10
MakeStyles	mount	1962	1951	50000
SpinButton	mount	2330	2316	5000