[Lint]Style: reformat markdown files via markdownlint (#5884)

### What this PR does / why we need it?
reformat markdown files via markdownlint

- vLLM version: v0.13.0
- vLLM main:
bde38c11df

---------

Signed-off-by: root <root@LAPTOP-VQKDDVMG.localdomain>
Signed-off-by: MrZ20 <2609716663@qq.com>
Co-authored-by: root <root@LAPTOP-VQKDDVMG.localdomain>

docs/source/developer_guide/contribution/index.md

@@ -1,6 +1,7 @@
 # Contributing
 
 ## Building and Testing
+
 It's recommended to set up a local development environment to build vllm-ascend and run tests
 before you submit a PR.