add cross references

Signed-off-by: Ruihang Xia <[email protected]>

docs/reference/http-endpoints.md

@@ -36,13 +36,13 @@ Endpoints that is not versioned (under `/v1`). For miscellaneous usage like heal
 
 ### Dashboard
 
-- **Paths**:
-  - `/dashboard`
-  - `/dashboard/`
+- **Paths**: `/dashboard`
 - **Methods**: `GET`, `POST`
 - **Description**: Provides access to the server's dashboard interface.
 - **Usage**: Access these endpoints to interact with the web-based dashboard.
 
+This dashboard is packaged with the GreptimeDB server and provides a user-friendly interface for interacting with the server. It requires corresponding compile flags to be enabled when building GreptimeDB. The original source code for the dashboard can be found in https://github.com/GreptimeTeam/dashboard
+
 ### Debugging Tools
 
 - **Base Path**: `/debug`
@@ -69,6 +69,8 @@ Various query APIs for sending query to GreptimeDB.
 - **Usage**:
   - `GET`: Send SQL queries via query parameters.
   - `POST`: Send SQL queries in the request body.
+
+For more information on the SQL API, refer to the [SQL documentation](../user-guide/query-data/sql.md).
 
 ### PromQL API
 
@@ -78,6 +80,8 @@ Various query APIs for sending query to GreptimeDB.
 - **Usage**:
   - `GET`: Send PromQL queries via query parameters.
   - `POST`: Send PromQL queries in the request body.
+
+For more information on the PromQL API, refer to the [PromQL documentation](../user-guide/query-data/promql.md).
 
 ## Protocol Endpoints
 
@@ -98,6 +102,8 @@ Endpoints for various protocols that are compatible with GreptimeDB. Like Influx
   - Ingest data using InfluxDB line protocol.
   - Use ping and health endpoints to check server status.
 
+The detailed documentation for InfluxDB protocol can be found [here](../user-guide/protocols/influxdb-line-protocol.md).
+
 ### Prometheus Remote Write/Read
 
 - **Paths**:
@@ -125,6 +131,8 @@ Endpoints for various protocols that are compatible with GreptimeDB. Like Influx
 - **Description**: Provides Prometheus HTTP API endpoints for querying and retrieving metric data.
 - **Usage**: Use these endpoints to interact with metrics using standard Prometheus HTTP API.
 
+Refer to the original Prometheus documentation for more information on the [Prometheus HTTP API](https://prometheus.io/docs/prometheus/latest/querying/api/).
+
 ### OpenTelemetry Protocol (OTLP)
 
 - **Paths**:
@@ -163,6 +171,8 @@ Endpoints for various protocols that are compatible with GreptimeDB. Like Influx
   - Ingest logs via the `/logs` endpoint.
   - Manage log pipelines using the `/pipelines` endpoints.
 
+For more information on log ingestion and pipeline management, refer to the [log overview](../user-guide/logs/overview.md).
+
 ## Scripts Endpoints
 
 ### Scripts Management

docs/user-guide/protocols/http.md

@@ -1,6 +1,6 @@
 # HTTP API
 
-GreptimeDB provides HTTP APIs for interacting with the database.
+GreptimeDB provides HTTP APIs for interacting with the database. For a complete list of available APIs, please refer to the [HTTP Endpoint](/reference/http-endpoints.md).
 
 ## Base URL