Docs: update for v0.19.0 (#7823)

### What problem does this PR solve?

update for v0.19.0

### Type of change

- [x] Documentation Update

docs/guides/chat/start_chat.md

@@ -48,7 +48,7 @@ You start an AI conversation by creating an assistant.
      - If no target language is selected, the system will search only in the language of your query, which may cause relevant information in other languages to be missed.
    - **Variable** refers to the variables (keys) to be used in the system prompt. `{knowledge}` is a reserved variable. Click **Add** to add more variables for the system prompt.
       - If you are uncertain about the logic behind **Variable**, leave it *as-is*.
-      - As of v0.18.0, if you add custom variables here, the only way you can pass in their values is to call:
+      - As of v0.19.0, if you add custom variables here, the only way you can pass in their values is to call:
          - HTTP method [Converse with chat assistant](../../references/http_api_reference.md#converse-with-chat-assistant), or
          - Python method [Converse with chat assistant](../../references/python_api_reference.md#converse-with-chat-assistant).
 

docs/guides/dataset/configure_knowledge_base.md

@@ -128,7 +128,7 @@ See [Run retrieval test](./run_retrieval_test.md) for details.
 
 ## Search for knowledge base
 
-As of RAGFlow v0.18.0, the search feature is still in a rudimentary form, supporting only knowledge base search by name.
+As of RAGFlow v0.19.0, the search feature is still in a rudimentary form, supporting only knowledge base search by name.
 
 ![search knowledge base](https://github.com/infiniflow/ragflow/assets/93570324/836ae94c-2438-42be-879e-c7ad2a59693e)
 

docs/guides/manage_files.md

@@ -87,4 +87,4 @@ RAGFlow's file management allows you to download an uploaded file:
 
 ![download_file](https://github.com/infiniflow/ragflow/assets/93570324/cf3b297f-7d9b-4522-bf5f-4f45743e4ed5)
 
-> As of RAGFlow v0.18.0, bulk download is not supported, nor can you download an entire folder. 
+> As of RAGFlow v0.19.0, bulk download is not supported, nor can you download an entire folder. 

docs/guides/tracing.mdx

@@ -18,7 +18,7 @@ RAGFlow ships with a built-in [Langfuse](https://langfuse.com) integration so th
 Langfuse stores traces, spans and prompt payloads in a purpose-built observability backend and offers filtering and visualisations on top.  
 
 :::info NOTE
-• RAGFlow **≥ 0.18.0** (contains the Langfuse connector)  
+• RAGFlow **≥ 0.19.0** (contains the Langfuse connector)  
 • A Langfuse workspace (cloud or self-hosted) with a _Project Public Key_ and _Secret Key_
 :::
 

docs/guides/upgrade_ragflow.mdx

@@ -66,16 +66,16 @@ To upgrade RAGFlow, you must upgrade **both** your code **and** your Docker imag
    git clone https://github.com/infiniflow/ragflow.git
    ```
 
-2. Switch to the latest, officially published release, e.g., `v0.18.0`:
+2. Switch to the latest, officially published release, e.g., `v0.19.0`:
 
    ```bash
-   git checkout -f v0.18.0
+   git checkout -f v0.19.0
    ```
 
 3. Update **ragflow/docker/.env** as follows:
 
    ```bash
-   RAGFLOW_IMAGE=infiniflow/ragflow:v0.18.0
+   RAGFLOW_IMAGE=infiniflow/ragflow:v0.19.0
    ```
 
 4. Update the RAGFlow image and restart RAGFlow:
@@ -92,10 +92,10 @@ To upgrade RAGFlow, you must upgrade **both** your code **and** your Docker imag
 1. From an environment with Internet access, pull the required Docker image.
 2. Save the Docker image to a **.tar** file.
    ```bash
-   docker save -o ragflow.v0.18.0.tar infiniflow/ragflow:v0.18.0
+   docker save -o ragflow.v0.19.0.tar infiniflow/ragflow:v0.19.0
    ```
 3. Copy the **.tar** file to the target server.
 4. Load the **.tar** file into Docker:
    ```bash
-   docker load -i ragflow.v0.18.0.tar
+   docker load -i ragflow.v0.19.0.tar
    ```