update docs (#536)

Signed-off-by: hsliu <liuhongsheng4@huawei.com>

docs/contributing/model/README.md

@@ -26,4 +26,4 @@ The guide covers:
 
 ## Quick Start
 
-For a quick reference, see the [Adding a New Omni Model Guide](adding_multi_stage_model.md) and [Adding a New Diffusion Model Guide](adding_diffusion_model.md).
+For a quick reference, see the [Adding a New Multi-Stage Model Guide](adding_multi_stage_model.md) and [Adding a New Diffusion Model Guide](adding_diffusion_model.md).

docs/contributing/model/adding_diffusion_model.md

@@ -1,4 +1,4 @@
-# Adding a New Diffusion Model to vLLM-Omni
+# Adding a Diffusion Model
 This guide walks through the process of adding a new Diffusion model to vLLM-Omni, using Qwen/Qwen-Image-Edit as a comprehensive example.
 
 # Table of Contents

docs/contributing/model/adding_multi_stage_model.md

@@ -1,6 +1,6 @@
-# Adding a New Multi-Stage Model to vLLM-Omni
+# Adding a Multi-Stage Model
 
-This guide walks through the process of adding a new model to vLLM-Omni, using **Qwen3-Omni** as a comprehensive example. Qwen3-Omni is a multi-stage omni-modality model that demonstrates the full capabilities of vLLM-Omni's architecture.
+This guide walks through the process of adding a new multi-stage model to vLLM-Omni, using **Qwen3-Omni** as a comprehensive example. Qwen3-Omni is a multi-stage omni-modality model that demonstrates the full capabilities of vLLM-Omni's architecture.
 
 ## Table of Contents