docs(sentry): Add dev docs for renderHookWithProviders (#14941)

Also adds docs about additionalWrapper

Author: scttcper

develop-docs/frontend/using-rtl.mdx

@@ -32,6 +32,22 @@ const organization = OrganizationFixture({access: ['org:admin'], features: ['my-
 render(<Example />, {organization});
 ```
 
+### Add extra providers
+
+If your component needs more context, pass an `additionalWrapper` to `render()` to compose extra providers inside our default test providers.
+
+```tsx
+import {render, screen} from "sentry-test/reactTestingLibrary";
+
+function MyExtraProviders({children}: {children: React.ReactNode}) {
+  return <SomeContext.Provider value={{}}>{children}</SomeContext.Provider>;
+}
+
+render(<Example />, {additionalWrapper: MyExtraProviders});
+
+expect(screen.getByText(/example/i)).toBeInTheDocument();
+```
+
 ## Testing route changes
 
 When using `render()`, an in-memory router is used, which will react to navigations with `useNavigate()` or interations with `Link` components. If your component relies on the URL, you can define the initial state in `initialRouterConfig`. You can access the current router state by referencing the returned `router` class, as well as navigate programmatically with `router.navigate()`.
@@ -221,3 +237,55 @@ import {render, screen, userEvent} from "sentry-test/reactTestingLibrary";
 render(<Example />);
 userEvent.type(screen.getByLabelText("Search by name"), "sentry");
 ```
+
+## Testing hooks with providers
+
+Use `renderHookWithProviders()` to test hooks with the same built-in providers as `render()` (organization, theme, query client, and an in-memory router). It returns the regular `renderHook` result plus a `router` helper you can use to inspect location and navigate.
+
+Set the initial URL and define route patterns via `initialRouterConfig` (use `route` for a single route or `routes` for multiple):
+
+```tsx
+import {useParams} from 'react-router-dom';
+import {renderHookWithProviders, waitFor} from 'sentry-test/reactTestingLibrary';
+
+function useRouteId() {
+  const {id} = useParams();
+  return id;
+}
+
+const {result, router} = renderHookWithProviders(useRouteId, {
+  initialRouterConfig: {
+    location: {pathname: '/foo/123/'},
+    route: '/foo/:id/',
+  },
+});
+
+expect(result.current).toBe('123');
+
+// Navigate programmatically
+router.navigate('/foo/456/');
+
+await waitFor(() => expect(result.current).toBe('456'));
+```
+
+You can also provide additional providers or override the default organization via options:
+
+```tsx
+import {OrganizationFixture} from 'sentry-fixture/organization';
+import {renderHookWithProviders} from 'sentry-test/reactTestingLibrary';
+
+function useFeatureFlag() {
+  // implementation under test
+}
+
+function MyExtraProviders({children}: {children: React.ReactNode}) {
+  return <SomeContext.Provider value={{}}>{children}</SomeContext.Provider>;
+}
+
+const organization = OrganizationFixture({features: ['my-feature-flag']});
+
+const {result} = renderHookWithProviders(useFeatureFlag, {
+  organization,
+  additionalWrapper: MyExtraProviders,
+});
+```