update simple node parser usage (#7370)

docs/core_modules/data_modules/documents_and_nodes/root.md

...a_modules/documents_and_nodes/usage_metadata_extractor.md

...e_modules/data_modules/documents_and_nodes/usage_nodes.md

docs/core_modules/data_modules/index/metadata_extraction.md

docs/core_modules/data_modules/node_parsers/usage_pattern.md

docs/core_modules/data_modules/storage/customization.md

docs/core_modules/data_modules/storage/docstores.md

docs/core_modules/supporting_modules/service_context.md

docs/examples/agent/openai_agent_query_cookbook.ipynb

docs/examples/callbacks/OpenInferenceCallback.ipynb

docs/examples/docstore/DocstoreDemo.ipynb

docs/examples/docstore/FirestoreDemo.ipynb

docs/examples/docstore/MongoDocstoreDemo.ipynb

docs/examples/docstore/RedisDocstoreIndexStoreDemo.ipynb

...es/index_structs/knowledge_graph/KnowledgeGraphDemo.ipynb

...xamples/index_structs/knowledge_graph/KuzuGraphDemo.ipynb

...ndex_structs/knowledge_graph/NebulaGraphKGIndexDemo.ipynb

...ples/index_structs/knowledge_graph/Neo4jKGIndexDemo.ipynb

.../examples/metadata_extraction/MetadataExtractionSEC.ipynb

docs/examples/query_engine/SQLAutoVectorQueryEngine.ipynb