[zh] translate image caption in multi cluster setup (#12872)

Signed-off-by: huangminjie <minjie.huang@daocloud.io>

content/zh/docs/setup/install/multicluster/multi-primary/index.md

@@ -19,7 +19,7 @@ owner: istio/wg-environments-maintainers
 
 {{< image width="75%"
     link="arch.svg"
-    caption="Multiple primary clusters on the same network"
+    caption="同一网络的多主集群"
     >}}
 
 ## 将 `cluster1` 设为主集群 {#configure-cluster1-as-a-primary}

content/zh/docs/setup/install/multicluster/multi-primary_multi-network/index.md

@@ -23,7 +23,7 @@ owner: istio/wg-environments-maintainers
 
 {{< image width="75%"
     link="arch.svg"
-    caption="Multiple primary clusters on separate networks"
+    caption="跨网络的多主集群"
     >}}
 
 ## 为 `cluster1` 设置缺省网络 {#set-the-default-network-for-cluster1}

content/zh/docs/setup/install/multicluster/primary-remote/index.md

@@ -26,7 +26,7 @@ owner: istio/wg-environments-maintainers
 
 {{< image width="75%"
     link="arch.svg"
-    caption="Primary and remote clusters on the same network"
+    caption="同一网络的主从集群"
     >}}
 
 ## 将 `cluster1` 设为主集群 {#configure-cluster1-as-a-primary}