Doc: Added an HTTP request component reference (#12141)

### Type of change

- [x] Documentation Update

docs/guides/agent/agent_component_reference/http.md

@@ -0,0 +1,90 @@
+---
+sidebar_position: 30
+slug: /http_request_component
+---
+
+# HTTP request component
+
+A component that calls remote services. 
+
+---
+
+An **HTTP request** component lets you access remote APIs or services by providing a URL and an HTTP method, and then receive the response. You can customize headers, parameters, proxies, and timeout settings, and use common methods like GET and POST. It’s useful for exchanging data with external systems in a workflow.
+
+## Prerequisites
+
+- An accessible remote API or service.
+- Add a Token or credentials to the request header, if the target service requires authentication.
+
+## Configurations
+
+### Url
+
+*Required*. The complete request address, for example: http://api.example.com/data.
+
+### Method
+
+The HTTP request method to select. Available options:
+
+- GET
+- POST
+- PUT
+
+### Timeout
+
+The maximum waiting time for the request, in seconds. Defaults to `60`.
+
+### Headers
+
+Custom HTTP headers can be set here, for example:
+
+```http
+{
+  "Accept": "application/json",
+  "Cache-Control": "no-cache",
+  "Connection": "keep-alive"
+}
+```
+
+### Proxy
+
+Optional. The proxy server address to use for this request.
+
+### Clean HTML
+
+`Boolean`: Whether to remove HTML tags from the returned results and keep plain text only.
+
+### Parameter
+
+*Optional*. Parameters to send with the HTTP request. Supports key-value pairs:
+
+- To assign a value using a dynamic system variable, set it as Variable.
+- To override these dynamic values under certain conditions and use a fixed static value instead, Value is the appropriate choice.
+
+
+:::tip NOTE
+- For GET requests, these parameters are appended to the end of the URL.
+- For POST/PUT requests, they are sent as the request body.
+:::
+
+#### Example setting
+
+![](https://raw.githubusercontent.com/infiniflow/ragflow-docs/main/images/http_settings.png)
+
+#### Example response
+
+```html
+{ "args": { "App": "RAGFlow", "Query": "How to do?", "Userid": "241ed25a8e1011f0b979424ebc5b108b" }, "headers": { "Accept": "/", "Accept-Encoding": "gzip, deflate, br, zstd", "Cache-Control": "no-cache", "Host": "httpbin.org", "User-Agent": "python-requests/2.32.2", "X-Amzn-Trace-Id": "Root=1-68c9210c-5aab9088580c130a2f065523" }, "origin": "185.36.193.38", "url": "https://httpbin.org/get?Userid=241ed25a8e1011f0b979424ebc5b108b&App=RAGFlow&Query=How+to+do%3F" }
+```
+
+### Output
+
+The global variable name for the output of the HTTP request component, which can be referenced by other components in the workflow.
+
+- `Result`: `string` The response returned by the remote service.
+
+## Example
+
+This is a usage example: a workflow sends a GET request from the **Begin** component to `https://httpbin.org/get` via the **HTTP Request_0** component, passes parameters to the server, and finally outputs the result through the **Message_0** component.
+
+![](https://raw.githubusercontent.com/infiniflow/ragflow-docs/main/images/http_usage.PNG)