docs: Clarify on API endpoints as data sources

docs/pages/product/configuration/data-sources.mdx

@@ -11,7 +11,7 @@ Choose a data source to get started with below.
 Note that Cube also supports connecting to [multiple data
 sources][ref-config-multi-data-src] out of the box.
 
-## Data Warehouses
+## Data warehouses
 
 <Grid imageSize={[56, 56]}>
   <GridItem
@@ -56,7 +56,7 @@ sources][ref-config-multi-data-src] out of the box.
   />
 </Grid>
 
-## Query Engines
+## Query engines
 
 <Grid imageSize={[56, 56]}>
   <GridItem
@@ -86,7 +86,7 @@ sources][ref-config-multi-data-src] out of the box.
   />
 </Grid>
 
-## Transactional Databases
+## Transactional databases
 
 <Grid imageSize={[56, 56]}>
   <GridItem
@@ -116,7 +116,7 @@ sources][ref-config-multi-data-src] out of the box.
   />
 </Grid>
 
-## Time Series Databases
+## Time series databases
 
 <Grid imageSize={[56, 56]}>
   <GridItem
@@ -146,7 +146,7 @@ sources][ref-config-multi-data-src] out of the box.
   />
 </Grid>
 
-## Other Data Sources
+## Other data sources
 
 <Grid imageSize={[56, 56]}>
   <GridItem
@@ -181,28 +181,45 @@ sources][ref-config-multi-data-src] out of the box.
   />
 </Grid>
 
-## Driver Support
+### API endpoints
+
+Cube is designed to work with data sources that allow querying them with SQL.
+
+Cube is not designed to access data files directly or fetch data from REST,
+or GraphQL, or any other API. To use Cube in that way, you either need to use
+a supported data source (e.g., use [DuckDB][ref-duckdb] to query Parquet files
+on Amazon S3) or create a [custom data source driver](#currently-unsupported-data-sources).
+
+## Data source drivers
+
+### Driver support
 
 Most of the drivers for data sources are supported either directly by the Cube
 team or by their vendors. The rest are community-supported and will be
 highlighted as such in their respective pages.
 
-## Third-party Drivers
+You can find the [source code][link-github-packages] of the drivers that are part
+of the Cube distribution in `cubejs-*-driver` folders on GitHub. 
+
+### Third-party drivers
 
 The following drivers were contributed by the Cube community. They are not part
 of the Cube distribution, however, they can still be used with Cube:
 
-- [CosmosDB driver](https://www.npmjs.com/package/cosmosdb-cubejs-driver)
-- [SAP Hana driver](https://www.npmjs.com/package/cubejs-hana-driver)
-- [ArangoDB driver](https://www.npmjs.com/package/arangodb-cubejs-driver)
-- [OpenDistro Elastic driver](https://www.npmjs.com/package/opendistro-cubejs-driver)
-- [Mydremio driver](https://www.npmjs.com/package/mydremio-cubejs-driver)
-- [Trino driver](https://www.npmjs.com/package/trino-cubejs-driver)
-- [Cratedb driver](https://www.npmjs.com/package/cratedb-cubejs-driver)
-- [Dremio ODBC driver](https://www.npmjs.com/package/dremio-odbc-cubejs-driver)
-- [Vertica Driver](https://www.npmjs.com/package/@knowitall/vertica-driver)
+- [ArangoDB](https://www.npmjs.com/package/arangodb-cubejs-driver)
+- [CosmosDB](https://www.npmjs.com/package/cosmosdb-cubejs-driver)
+- [CrateDB](https://www.npmjs.com/package/cratedb-cubejs-driver)
+- [Dremio](https://www.npmjs.com/package/mydremio-cubejs-driver)
+- [Dremio ODBC](https://www.npmjs.com/package/dremio-odbc-cubejs-driver)
+- [OpenDistro Elastic](https://www.npmjs.com/package/opendistro-cubejs-driver)
+- [SAP Hana](https://www.npmjs.com/package/cubejs-hana-driver)
+- [Trino](https://www.npmjs.com/package/trino-cubejs-driver)
+- [Vertica](https://www.npmjs.com/package/@knowitall/vertica-driver)
+
+You need to configure [`driver_factory`][ref-driver-factory] to use a third-party
+driver.
 
-## Currently Unsupported Data Sources
+### Currently unsupported data sources
 
 If you'd like to connect to a data source which is not yet listed on this page,
 please see the list of [requested drivers](https://github.com/cube-js/cube/issues/7076)
@@ -244,5 +261,8 @@ using the `CUBEJS_DB_MAX_POOL` environment variable; if changing this from the
 default, you must ensure that the new value is greater than the number of
 concurrent connections used by Cube's query queues and refresh scheduler.
 
-[ref-config-multi-data-src]:
-  /product/configuration/advanced/multiple-data-sources
+
+[ref-config-multi-data-src]: /product/configuration/advanced/multiple-data-sources
+[ref-driver-factory]: /reference/configuration/config#driver_factory
+[ref-duckdb]: /product/configuration/data-sources/duckdb
+[link-github-packages]: https://github.com/cube-js/cube/tree/master/packages