Add 'vllm' tag

## Add tag: vllm

This PR adds the `vllm` tag to the model repository.

**Changes:**
- Added `vllm` to model tags
- Updated from 4 to 5 tags

**Current tags:** play, fake, region:us, test-tag
**New tags:** play, fake, region:us, test-tag, vllm

README.md

@@ -4,4 +4,5 @@ tags:
 - fake
 - region:us
 - test-tag
+- vllm
 ---