Add AstraDB RAG Flow guide

docs/src/theme/DownloadableJsonFile.js

@@ -0,0 +1,29 @@
+const DownloadableJsonFile = ({ source, title }) => {
+  const handleDownload = (event) => {
+    event.preventDefault();
+    fetch(source)
+      .then((response) => response.blob())
+      .then((blob) => {
+        const url = window.URL.createObjectURL(
+          new Blob([blob], { type: "application/json" })
+        );
+        const link = document.createElement("a");
+        link.href = url;
+        link.setAttribute("download", title);
+        document.body.appendChild(link);
+        link.click();
+        link.parentNode.removeChild(link);
+      })
+      .catch((error) => {
+        console.error("Error downloading file:", error);
+      });
+  };
+
+  return (
+    <a href={source} download={title} onClick={handleDownload}>
+      {title}
+    </a>
+  );
+};
+
+export default DownloadableJsonFile;