[exporter/googlecloudstorageexporter] docs: fixed example with 'bucket' instead of the wrong 'storage'

Author: ctorrao

exporter/googlecloudstorageexporter/README.md

@@ -33,7 +33,7 @@ Here is an example configuration for this exporter:
 exporters:
   googlecloudstorage:
     encoding: text_encoding
-    storage:
+    bucket:
       name: bucket-test
       project_id: project-test
       reuse_if_exists: true
@@ -42,4 +42,4 @@ exporters:
 extensions:
   # text encoding to ensure only the body is placed in the bucket
   text_encoding:
-```
+```