Sort books by rating.

app/gatsby-node.js

@@ -12,6 +12,10 @@ exports.createPages = async function ({ actions, graphql }) {
                     eq: $categoryName
                 }
             }
+            sort: {
+              fields: [rating]
+              order: DESC
+            }
         ){
           edges {
             node {

app/src/pages/index.js

@@ -43,7 +43,12 @@ export default ({ data }) => {
 
 export const query = graphql`
   query MyQuery {
-    allBooksJson {
+    allBooksJson(
+      sort: {
+        fields: [rating]
+        order: DESC
+      }
+    ) {
       edges {
         node {
           id