Preparation for release. (#4739)

### What problem does this PR solve?


### Type of change

- [x] Documentation Update

docs/guides/configure_knowledge_base.md

@@ -128,7 +128,7 @@ RAGFlow uses multiple recall of both full-text search and vector search in its c
 
 ## Search for knowledge base
 
-As of RAGFlow v0.15.1, the search feature is still in a rudimentary form, supporting only knowledge base search by name.
+As of RAGFlow v0.16.0, 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

@@ -81,4 +81,4 @@ 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 v0.15.1, bulk download is not supported, nor can you download an entire folder. 
+> As of RAGFlow v0.16.0, bulk download is not supported, nor can you download an entire folder. 

docs/guides/upgrade_ragflow.mdx

@@ -62,16 +62,16 @@ 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., `v0.15.1`:
+2. Switch to the latest, officially published release, e.g., `v0.16.0`:
 
    ```bash
-   git checkout -f v0.15.1
+   git checkout -f v0.16.0
    ```
 
 3. Update **ragflow/docker/.env** as follows:
 
    ```bash
-   RAGFLOW_IMAGE=infiniflow/ragflow:v0.15.1
+   RAGFLOW_IMAGE=infiniflow/ragflow:v0.16.0
    ```
 
 4. Update the RAGFlow image and restart RAGFlow: