[Doc] add tls check to pd disaggregation readme (#5638)

### What this PR does / why we need it?

update pd disaggregation multi_node readme, update the environment check
command for A3, add tls check
### Does this PR introduce _any_ user-facing change?

### How was this patch tested?


- vLLM version: v0.13.0
- vLLM main:
8be6432bda

Signed-off-by: liziyu <liziyu16@huawei.com>

docs/source/tutorials/pd_disaggregation_mooncake_single_node.md

@@ -27,7 +27,7 @@ for i in {0..7}; do hccn_tool -i $i -netdetect -g ; done
 for i in {0..7}; do hccn_tool -i $i -gateway -g ; done
 ```
 
-2. Check NPU network configuration:
+2. Check NPU HCCN Configuration:
 
 Ensure that the hccn.conf file exists in the environment. If using Docker, mount it into the container.
 
@@ -41,6 +41,20 @@ cat /etc/hccn.conf
 for i in {0..7}; do hccn_tool -i $i -ip -g;done
 ```
 
+4. Cross-Node PING Test
+
+```bash
+# Execute on the target node (replace 'x.x.x.x' with actual npu ip address)
+for i in {0..7}; do hccn_tool -i $i -ping -g address x.x.x.x;done
+```
+
+5. Check NPU TLS Configuration
+
+```bash
+# The tls settings should be consistent across all nodes
+for i in {0..7}; do hccn_tool -i $i -tls -g ; done | grep switch
+```
+
 ## Run with Docker
 Start a Docker container.