docs(getting-started): Update Getting Started documentation path

- Change 'getting_started.md' to 'getting-started.md' in mkdocs.yml
- This update aligns with the new documentation structure

Author: codeboyzhou

docs/docs/getting_started.md renamed to docs/docs/getting-started.md

@@ -67,4 +67,4 @@ extra:
 
 nav:
   - Overview: index.md
-  - Getting Started: getting_started.md
+  - Getting Started: getting-started.md