docs: update the cuda docstring (tensorchord#1641)

Signed-off-by: Keming <[email protected]>

Author: kemingy

envd/api/v1/__init__.py

@@ -43,7 +43,7 @@ def base(image: str = "ubuntu:20.04", dev: bool = False):
     """
 
 
-def shell(name: str = "base"):
+def shell(name: str = "bash"):
     """Interactive shell
 
     Args:

envd/api/v1/install.py

@@ -114,7 +114,10 @@ def vscode_extensions(name: List[str]):
 
 
 def cuda(version: str, cudnn: Optional[str] = "8"):
-    """Install CUDA dependency
+    """Replace the base image with a `nvidia/cuda` image.
+
+    If you want to install CUDA on your custom base image, you can use
+    `install.apt_packages` or `run` to install the CUDA toolkit.
 
     Args:
         version (str): CUDA version, such as '11.6.2'