feat(v2): allow adding components to react-live scope (#2826)

* feat(v2): add components to react-live scope (#2807)

* fix admonition issue + improve react-live scope doc

* fix again admonition :(

* remove forwarding of mdx components to react-live scope (for now)

* remove useless dep

website/src/theme/ReactLiveScope/components.js

@@ -0,0 +1,15 @@
+import React from 'react';
+
+export const ButtonExample = (props) => (
+  <button
+    {...props}
+    style={{
+      backgroundColor: 'white',
+      border: 'solid red',
+      borderRadius: 20,
+      padding: 10,
+      cursor: 'pointer',
+      ...props.style,
+    }}
+  />
+);

website/src/theme/ReactLiveScope/index.js

@@ -0,0 +1,18 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import React from 'react';
+import * as components from './components';
+
+// Add react-live imports you need here
+const ReactLiveScope = {
+  React,
+  ...React,
+  ...components,
+};
+
+export default ReactLiveScope;