chore: import upstream snapshot with attribution

dev-docs/src/theme/MDXComponents.js

@@ -0,0 +1,11 @@
+// Import the original mapper
+import Highlight from "@site/src/components/Highlight";
+import MDXComponents from "@theme-original/MDXComponents";
+
+export default {
+  // Re-use the default mapping
+  ...MDXComponents,
+  // Map the "highlight" tag to our <Highlight /> component!
+  // `Highlight` will receive all props that were passed to `highlight` in MDX
+  highlight: Highlight,
+};