[Docs][skip ci] Fix omni and tts docs (#2130)

Signed-off-by: gcanlin <canlinguosdu@gmail.com>

docs/getting_started/installation/npu/npu.inc.md

@@ -73,7 +73,6 @@ cd /vllm-workspace/vllm
 git pull origin main
 git fetch origin --tags
 git checkout v0.18.0
-VLLM_TARGET_DEVICE=empty pip install -v -e .
 
 # Because vllm-ascend has not yet entered continuous development and has not been officially released, we need to pin it to a specific commit. Please note that this commit may change over time.
 cd /vllm-workspace/vllm-ascend
@@ -83,8 +82,8 @@ git checkout 1e05c4908f31737bc4eef865a9f351d030a77c9d
 pip install -v -e .
 
 # Install vLLM-Omni from the latest main branch
-cd /vllm-workspace/vllm-omni
 git clone https://github.com/vllm-project/vllm-omni.git
+cd /vllm-workspace/vllm-omni
 pip install -v -e . --no-build-isolation
 # or VLLM_OMNI_TARGET_DEVICE=npu pip install -v -e .
 export VLLM_WORKER_MULTIPROC_METHOD=spawn