chore(gatsby-source-wordpress): Correct glob pattern examples (#11804)

## Description

Adds a test for a route blog pattern that is working both on custom hosted WordPress API paths and on API paths from sites  that are hosted on wordpress.com.

## Related Issues

This is picking up the discussion on the routes documentation within #10871 and the according pull request #10887.

packages/gatsby-source-wordpress/README.md

@@ -119,16 +119,16 @@ module.exports = {
         // all routes that begin with `yoast` from fetch.
         // Whitelisted routes using glob patterns
         includedRoutes: [
-          "**/*/*/categories",
-          "**/*/*/posts",
-          "**/*/*/pages",
-          "**/*/*/media",
-          "**/*/*/tags",
-          "**/*/*/taxonomies",
-          "**/*/*/users",
+          "**/categories",
+          "**/posts",
+          "**/pages",
+          "**/media",
+          "**/tags",
+          "**/taxonomies",
+          "**/users",
         ],
         // Blacklisted routes using glob patterns
-        excludedRoutes: ["**/*/*/posts/1456"],
+        excludedRoutes: ["**/posts/1456"],
         // use a custom normalizer which is applied after the built-in ones.
         normalizer: function({ entities }) {
           return entities
@@ -199,13 +199,13 @@ If an endpoint is whitelisted and not blacklisted, it will be fetched. Otherwise
 
 ```javascript
 includedRoutes: [
-  "**/*/*/posts",
-  "**/*/*/pages",
-  "**/*/*/media",
-  "**/*/*/categories",
-  "**/*/*/tags",
-  "**/*/*/taxonomies",
-  "**/*/*/users",
+  "**/posts",
+  "**/pages",
+  "**/media",
+  "**/categories",
+  "**/tags",
+  "**/taxonomies",
+  "**/users",
 ],
 ```