refine document by using latest as version number (infiniflow#588)

### What problem does this PR solve?

### Type of change

- [x] Documentation Update

docker/.env

@@ -27,7 +27,7 @@ MINIO_PASSWORD=infini_rag_flow
 
 SVR_HTTP_PORT=9380
 
-RAGFLOW_VERSION=v0.4.0
+RAGFLOW_VERSION=latest
 
 TIMEZONE='Asia/Shanghai'
 

docs/faq.md

@@ -55,7 +55,7 @@ This feature and the related APIs are still in development. Contributions are we
 ```
 $ git clone https://github.com/infiniflow/ragflow.git
 $ cd ragflow
-$ docker build -t infiniflow/ragflow:v0.4.0 .
+$ docker build -t infiniflow/ragflow:latest .
 $ cd ragflow/docker
 $ chmod +x ./entrypoint.sh
 $ docker compose up -d
@@ -212,7 +212,7 @@ $ docker ps
 *The system displays the following if all your RAGFlow components are running properly:* 
 
 ```
-5bc45806b680   infiniflow/ragflow:v0.4.0     "./entrypoint.sh"        11 hours ago   Up 11 hours               0.0.0.0:80->80/tcp, :::80->80/tcp, 0.0.0.0:443->443/tcp, :::443->443/tcp, 0.0.0.0:9380->9380/tcp, :::9380->9380/tcp   ragflow-server
+5bc45806b680   infiniflow/ragflow:latest     "./entrypoint.sh"        11 hours ago   Up 11 hours               0.0.0.0:80->80/tcp, :::80->80/tcp, 0.0.0.0:443->443/tcp, :::443->443/tcp, 0.0.0.0:9380->9380/tcp, :::9380->9380/tcp   ragflow-server
 91220e3285dd   docker.elastic.co/elasticsearch/elasticsearch:8.11.3   "/bin/tini -- /usr/l…"   11 hours ago   Up 11 hours (healthy)     9300/tcp, 0.0.0.0:9200->9200/tcp, :::9200->9200/tcp           ragflow-es-01
 d8c86f06c56b   mysql:5.7.18        "docker-entrypoint.s…"   7 days ago     Up 16 seconds (healthy)   0.0.0.0:3306->3306/tcp, :::3306->3306/tcp     ragflow-mysql
 cd29bcb254bc   quay.io/minio/minio:RELEASE.2023-12-20T01-00-02Z       "/usr/bin/docker-ent…"   2 weeks ago    Up 11 hours      0.0.0.0:9001->9001/tcp, :::9001->9001/tcp, 0.0.0.0:9000->9000/tcp, :::9000->9000/tcp     ragflow-minio