chore(docs): Update processing external images guide (#34388)

* initial

* Revert "initial"

This reverts commit 3794b9c.

* update doc

docs/docs/how-to/images-and-media/preprocessing-external-images.md

@@ -57,9 +57,8 @@ exports.createSchemaCustomization = ({ actions }) => {
 exports.onCreateNode = async ({
   node,
   actions: { createNode, createNodeField },
-  store,
-  cache,
   createNodeId,
+  getCache,
 }) => {
   // For all MarkdownRemark nodes that have a featured image url, call createRemoteFileNode
   if (
@@ -71,8 +70,7 @@ exports.onCreateNode = async ({
       parentNodeId: node.id, // id of the parent node of the fileNode you are going to create
       createNode, // helper function in gatsby-node to generate the node
       createNodeId, // helper function in gatsby-node to generate the node id
-      cache, // Gatsby's cache
-      store, // Gatsby's Redux store
+      getCache,
     })
 
     // if the file was created, extend the node with "localFile"