add stream&task&external func to guides (#896)

* add stream&task&external func to guides

* Update index.md

* Update index.md

Author: BohuTANG

docs/en/guides/00-overview/index.md

@@ -18,6 +18,9 @@ Welcome to the Databend Guides, covering all aspects of Databend Editions.
 - **[Connect](../30-sql-clients/index.md)**: Connecting to Databend(Cloud) using various drivers.
 - **[Data Loading](../40-load-data/index.md)**: Bulk import data into Databend(Cloud) in multiple formats.
 - **[Data Unloading](../50-unload-data/index.md)**: Export data from Databend(Cloud).
+- **[Real-Time CDC Ingestion](../40-load-data/05-continuous-data-pipelines/01-stream.md)**: Change Data Capture (CDC) for real-time data ingestion.
+- **[Automated Data Pipelines](../40-load-data/05-continuous-data-pipelines/02-task.md)**: Create tasks to automate and manage continuous data pipelines.
+- **[External Functions](../54-query/04-external-function.md)**: Use external functions to extend Databend's capabilities.
 - **[Security](../56-security/index.md)**: Security features in Databend(Cloud).
 - **[Visualization](../31-visualize/index.md)**: Use visualization tools with Databend(Cloud).
 - **[Benchmarks](../80-benchmark/index.md)**: Compare Databend Cloud performance with Snowflake on TPC-H SF100 benchmarks.