Separate two entry points: Engine and HTTP server (#2996)

Co-authored-by: fzyzcjy <5236035+fzyzcjy@users.noreply.github.com>

docs/references/supported_models.md

@@ -91,7 +91,7 @@ Here is how you can do it:
 
 ```python
 from sglang.srt.models.registry import ModelRegistry
-from sglang.srt.server import launch_server
+from sglang.srt.entrypoints.http_server import launch_server
 
 # for a single model, you can add it to the registry
 ModelRegistry.models[model_name] = model_class