Remove unused files - src/theme/MDXComponents.js wraps instead of ejects during swizzle

src/theme/MDXComponents.js

@@ -0,0 +1,18 @@
+// Import the original mapper
+import MDXComponents from '@theme-original/MDXComponents';
+
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+import { CardSection, Card } from '../components/CardComponents';
+
+export default {
+  // Re-use the default mapping
+  ...MDXComponents,
+
+  Tabs: Tabs,
+  TabItem: TabItem,
+
+  CardSection,
+  Card,
+};