[Bugfix] fix ZeroDivisionError when prefill_tp_size > num_kv_head and fix tp_resharding README (#3437)

### What this PR does / why we need it?
Fix ZeroDivisionError when prefill_tp_size > num_kv_head, in this
situation, num_head_replica can be 0 and used to divide another value,
this PR restricts the minimum value of a to be 1. And this PR fix
tp_resharding README.

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
By CI.

- vLLM version: v0.11.0rc3
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0

---------

Signed-off-by: liziyu <liziyu16@huawei.com>
Signed-off-by: nwpu-zxr <zhouxuerong2@huawei.com>
Co-authored-by: liziyu <liziyu16@huawei.com>

vllm_ascend/distributed/mooncake_layerwise_connector.py

@@ -360,7 +360,7 @@ class SendingLayerThread(threading.Thread):
         remote_kv_base_addrs = req_meta.kv_caches_base_addr
 
         remote_block_ids = req_meta.block_ids
-        if self.num_head_replica >= 1 and self.tp_rank % self.num_head_replica != 0:
+        if self.tp_rank % self.num_head_replica != 0:
             pass
         elif self.pd_head_ratio == 1:
             layer_local_kv_base_addr = [