Theme provider docs

[micahgodbolt]

Theme provider docs don't make it clear that it only accepts standard HTML elements. (Issue here https://github.com/microsoft/fluentui/issues/28016)

This PR improves the docs to make it more clear, but also curious if we need to address the type.

[size-auditor[bot]]

Asset size changes

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

Baseline commit: d640b972d7ac86bfb76ae6c6329f12cdd33b3b7c (build)

[codesandbox-ci[bot]]

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 4fda4f6a7679e23e630a2139edbd3b2ae11708cc:

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

[fabricteam]

🕵 fluentuiv8 No visual regressions between this PR and main

[fabricteam]

📊 Bundle size report

_{🤖 This report was generated against d640b972d7ac86bfb76ae6c6329f12cdd33b3b7c}

[fabricteam]

Perf Analysis (@fluentui/react)

No significant results to display.

All results

Scenario	Render type	Master Ticks	PR Ticks	Iterations	Status
BaseButton	mount	619	593	5000
Breadcrumb	mount	1680	1591	1000
Checkbox	mount	1714	1635	5000
CheckboxBase	mount	1404	1492	5000
ChoiceGroup	mount	2960	2856	5000
ComboBox	mount	651	641	1000
CommandBar	mount	5913	5991	1000
ContextualMenu	mount	11273	11411	1000
DefaultButton	mount	703	718	5000
DetailsRow	mount	2095	2144	5000
DetailsRowFast	mount	2110	2067	5000
DetailsRowNoStyles	mount	1942	1928	5000
Dialog	mount	2427	2469	1000
DocumentCardTitle	mount	217	214	1000
Dropdown	mount	1918	1901	5000
FocusTrapZone	mount	1069	1078	5000
FocusZone	mount	1005	1011	5000
GroupedList	mount	39714	39982	2
GroupedList	virtual-rerender	17106	18911	2
GroupedList	virtual-rerender-with-unmount	48516	47985	2
GroupedListV2	mount	220	217	2
GroupedListV2	virtual-rerender	219	197	2
GroupedListV2	virtual-rerender-with-unmount	211	213	2
IconButton	mount	1022	1072	5000
Label	mount	327	333	5000
Layer	mount	2541	2577	5000
Link	mount	372	368	5000
MenuButton	mount	874	891	5000
MessageBar	mount	20311	20186	5000
Nav	mount	1876	1837	1000
OverflowSet	mount	738	723	5000
Panel	mount	1694	1662	1000
Persona	mount	689	708	1000
Pivot	mount	819	868	1000
PrimaryButton	mount	852	820	5000
Rating	mount	4362	4429	5000
SearchBox	mount	881	901	5000
Shimmer	mount	1816	1813	5000
Slider	mount	1292	1253	5000
SpinButton	mount	2814	2710	5000
Spinner	mount	381	353	5000
SplitButton	mount	1718	1741	5000
Stack	mount	396	406	5000
StackWithIntrinsicChildren	mount	822	804	5000
StackWithTextChildren	mount	2523	2558	5000
SwatchColorPicker	mount	5898	5886	5000
TagPicker	mount	1410	1365	5000
Text	mount	353	353	5000
TextField	mount	908	925	5000
ThemeProvider	mount	807	783	5000
ThemeProvider	virtual-rerender	555	562	5000
ThemeProvider	virtual-rerender-with-unmount	1219	1243	5000
Toggle	mount	583	561	5000
buttonNative	mount	178	189	5000