chore: update

Author: cyyeh

packages/doc/docs/develop/api-doc.mdx

@@ -4,6 +4,11 @@ In this section, we will discuss how VulcanSQL automatically generates API docum
 VulcanSQL automatically generates and serves the API documentation for you. To view the documentation, navigate to `<vulcan-endpoint>/doc` after starting the VulcanSQL server. From this page, you can also download the API specification in the Swagger format.
 
 ## Setting Sampler
+
+:::caution
+If [caching is enabled](../develop/cache) in the API endpoint, the sampling funcaionality is disabled.
+:::
+
 VulcanSQL offers a powerful feature called `sampler` that allows us to infer the response format by sending a sample query to your data warehouse. To enable this feature, you can set the sample property in each configuration file. For example:
 
 ```yaml title="artist.yaml"

packages/doc/docs/develop/cache.mdx

@@ -16,6 +16,8 @@ cache:
   type: parquet
   folderPath: tmp
   loader: duckdb
+extensions:
+  duckdb: @vulcan-sql/extension-driver-duckdb
 ```
 
  In the configuration, `tmp` means there will be a new folder called `tmp` in the root directory of the project you created.

packages/doc/docs/references/api-schema.mdx

@@ -26,7 +26,8 @@ Here is the introduction of each field in the API Schema.
 ### `urlPath` Field
 
 This is the Data API endpoint URL path. You could add the path parameter here using the `:[param-name]` format.
-If you forgot to add the `fieldName` and `filedIn` only if it's not `header`, VulcanSQL will auto generate it to make it work.
+There are [three types of values in the `fieldIn` field](#request-fields), namely `path`, `query` and `header`. 
+If the value is `header`, you are required to fill in the request parameters. VulcanSQL will auto generate other two values.
 
 ```yaml
 urlPath: /users/:id
@@ -118,6 +119,10 @@ For further details of using the `sample` field, please check out the section of
 
 :::
 
+:::caution
+If [caching is enabled](../develop/cache) in the API endpoint, the sampling funcaionality is disabled.
+:::
+
 ### `profiles` / `profile` field
 
 The `profiles` / `profile` indicate what data sources the APIs use to query the data.
@@ -139,6 +144,13 @@ Like the above example, if user3 would like to query data from APIs, he doesn't
 
 If you specify the `profiles` field, it could support multiple data sources like the below example:
 
+:::caution
+As the moment, in each SQL file, VulcanSQL only supports one data source, 
+but the data source used for caching is excluded.
+So, in any case you can add DuckDB as the caching layer.
+
+:::
+
 ```yaml
 urlPath: user/:id
 request: ...

packages/doc/docs/references/project-configurations.mdx

@@ -215,4 +215,4 @@ response-format:
 
 Every built-in extension has its configuration, but you don't need to define all of them manually because we have default configurations for most of them.
 
-For the above configuration, if you are interested, you could see [Data Source Profile](./data-source-profile), [Rate Limit](../api-plugin/rate-limit), Enforce HTTPS, [Response Format](../api-plugin/format), [Authentication](../data-privacy/authn) first.
+For the above configuration, if you are interested, you could see [Data Source Profile](./data-source-profile), [Rate Limit](../api-plugin/rate-limit), Enforce HTTPs, [Response Format](../api-plugin/format), [Authentication](../data-privacy/authn) first.