Fix trailing whitespace

04_image/4.3_rm.md

@@ -93,19 +93,19 @@ Docker 会检测镜像是否有容器依赖或其他标签指向，只有在确
 ```mermaid
 flowchart TD
     Start(["docker rmi redis:alpine"]) --> Step1
-    
+
     subgraph Process ["删除流程"]
         direction TB
         Step1["1. Untag：移除 redis:alpine 标签"] --> Step2
-        
+
         Step2{"2. 检查是否还有其他标签指向此镜像"}
         Step2 -- "有" --> Keep1["只 Untag，不删除"]
         Step2 -- "无" --> Step3
-        
+
         Step3{"3. 检查是否有容器依赖"}
         Step3 -- "有" --> Error["报错，无法删除"]
         Step3 -- "无" --> Step4
-        
+
         Step4{"4. 从上到下逐层删除，检查每层是否被其他镜像使用"}
         Step4 -- "被使用" --> Keep2["保留该层"]
         Step4 -- "未使用" --> Delete["Deleted (删除该层)"]
@@ -172,7 +172,7 @@ $ docker image prune -a --filter "until=168h"  # 7天前
 
 ```bash
 $ docker rmi nginx
-Error: conflict: unable to remove repository reference "nginx" 
+Error: conflict: unable to remove repository reference "nginx"
 (must force) - container abc123 is using its referenced image
 ```
 **解决方案**：