Miscellaneous doc updates and refactored team management doc. (#6730)

### What problem does this PR solve?

#5576, #6672

### Type of change


- [x] Documentation and UI Update

docs/guides/upgrade_ragflow.mdx

@@ -3,12 +3,16 @@ sidebar_position: 11
 slug: /upgrade_ragflow
 ---
 
-# Upgrade
+# Upgrading
 import Tabs from '@theme/Tabs';
 import TabItem from '@theme/TabItem';
 
 Upgrade RAGFlow to `nightly-slim`/`nightly` or the latest, published release.
 
+:::info NOTE
+Upgrading RAGFlow in itself will *not* remove your uploaded/historical data. However, be aware that `docker compose -f docker/docker-compose.yml down -v` will remove Docker container volumes, resulting in data loss.
+:::
+
 ## Upgrade RAGFlow to `nightly-slim`/`nightly`, the most recent, tested Docker image
 
 `nightly-slim` refers to the RAGFlow Docker image *without* embedding models, while `nightly` refers to the RAGFlow Docker image with embedding models. For details on their differences, see [ragflow/docker/.env](https://github.com/infiniflow/ragflow/blob/main/docker/.env).
@@ -79,4 +83,19 @@ To upgrade RAGFlow, you must upgrade **both** your code **and** your Docker imag
    ```bash
    docker compose -f docker/docker-compose.yml pull
    docker compose -f docker/docker-compose.yml up -d
-   ```
+   ```
+
+## Frequently asked questions
+
+### Upgrade RAGFlow in an offline environment (without Internet access)
+
+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.v0.17.2.tar infiniflow/ragflow:v0.17.2
+   ```
+3. Copy the **.tar** file to the target server.
+4. Load the **.tar** file into Docker:
+   ```bash
+   docker load -i ragflow.v0.17.2.tar
+   ```