docs: Add "scenarios" code examples (#1445)

docs/examples/error_fallback/README.md

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+# Error handling
+
+The built-in [`ErrorFallback`](../../reference/components/#django_components.components.error_fallback.ErrorFallback) component catches errors during component rendering and displays fallback content instead. This is similar to React's [`ErrorBoundary`](https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary) component.
+
+In this scenario, we have a `WeatherWidget` component that simulates fetching data from a weather API,
+which we wrap in the built-in [`ErrorFallback`](../../reference/components/#django_components.components.error_fallback.ErrorFallback) component.
+
+We have two cases:
+
+1. API call succeeds. The `WeatherWidget` component renders the weather information as expected.
+2. API call fails. The `ErrorFallback` component catches the error and display a user-friendly message instead of breaking the page.
+
+```django
+{% component "error_fallback" %}
+    {% fill "content" %}
+        {% component "weather_widget" location="Atlantis" / %}
+    {% endfill %}
+    {% fill "fallback" %}
+        <p style="color: red;">
+            Could not load weather data for <strong>Atlantis</strong>.
+            The location may not be supported or the service is temporarily down.
+        </p>
+    {% endfill %}
+{% endcomponent %}
+```
+
+![ErrorFallback example](./images/error_fallback.png)
+
+## Definition
+
+```djc_py
+--8<-- "docs/examples/error_fallback/component.py"
+```
+
+## Example
+
+To see the component in action, you can set up a view and URL pattern as shown below.
+
+### `views.py`
+
+```djc_py
+--8<-- "docs/examples/error_fallback/page.py"
+```
+
+### `urls.py`
+
+```python
+from django.urls import path
+
+from examples.pages.error_fallback import ErrorFallbackPage
+
+urlpatterns = [
+    path("examples/error_fallback", ErrorFallbackPage.as_view(), name="error_fallback"),
+]
+```