chore:(docs) New Component doc (#31611)

docs/react-v9/contributing/new-components.md

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+# Contributing a new component to Fluent UI React
+
+Our components are a collection of small, independent, general-purpose UI components intended to be reused throughout an application.
+
+## Questions to ask before starting to build a new component
+
+### Does the component already exist?
+
+Before making the decision to design a new component, check to see if the pattern already exists within any current Microsoft design system including our Figma toolkit. Please feel free to open Github issues to clarify doubts.
+
+If you are a Microsoft employee please check the internal version of the Figma toolkit or if you have more in depth questions regarding any Microsoft design system, please visit our internal Microsoft [Teams channel](https://teams.microsoft.com/l/channel/19%3ab743ef5589594c2e8a28b720003cb2ea%40thread.skype/Design?groupId=ffe264f2-14d0-48b5-9384-64f808b81294&tenantId=72f988bf-86f1-41af-91ab-2d7cd011db47).
+
+### Is the proposed component a variant of an existing component?
+
+If the new component pattern you are proposing already exists, but varies slightly, then please consider creating a variant of the component. For example, if you were to create a new button that does one new thing for our existing button then we would suggest creating a variant off the original button, but containing the one additional feature. The **Button** component is a good example of this. It has multiple variants like the **ActionButton**, **PrimaryButton**, **CommandBarButton** each of which is a very small component in itself. They all use the **BaseButton** for the core implementation but apply specific variations.
+
+### Should it be a shared component?​
+
+If it’s a new component request, does it add value at a broad level or is it a product-specific customization?​ Product-specific customizations should be stored in local product repos.
+
+There are also certain components which should only be used in first-party Microsoft products and therefore are not appropriate to include in a public component library. A commonly requested example is the Microsoft 365 suite header/nav bar (containing the app switcher, settings, etc).
+
+### Does this pattern contain Microsoft Intellectual Property?
+
+If the new component contains Microsoft Intellectual Property, it should be considered Internal and therefore all discussions around the component should **only** happen internally or within our [Fluent Design Teams channel](https://teams.microsoft.com/l/channel/19%3ab743ef5589594c2e8a28b720003cb2ea%40thread.skype/Design?groupId=ffe264f2-14d0-48b5-9384-64f808b81294&tenantId=72f988bf-86f1-41af-91ab-2d7cd011db47). If the component does not contain Microsoft Intellectual Property then this component can be discussed directly on GitHub in our [issues section](https://github.com/microsoft/fluentui/issues).
+
+### Get started 🎉
+
+Follow the component [implementation guide](component-implementation-guide.md) for the technical path forward for creating a new component.