doc: Add universe api doc (#374)

Signed-off-by: Jinjing.Zhou <allenzhou@tensorchord.ai>

envd/api/__init__.py

@@ -12,3 +12,42 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+"""Global functions"""
+
+from typing import Optional
+
+
+def base(os: str, language: str):
+    """Set base image
+    Args:
+        os (str): The operating system(i.e. `ubuntu20.04`)
+        language (str): The programing language dependency(i.e. `python3.8`)
+    """
+    pass
+
+
+def shell(name: str):
+    """Interactive shell 
+    Args:
+        name (str): shell name(i.e. `zsh`)
+    """
+    pass
+
+
+def run(commands: str):
+    """Execute command
+    Args:
+        commands (str): command to run
+    """
+    pass
+
+
+def git_config(name: Optional[str] = None,
+               email: Optional[str] = None, editor: Optional[str] = None):
+    """Setup git config
+    Args:
+        name (optional, str): User name
+        email (optional, str): User email
+        editor (optional, str): Editor for git operations
+    """
+    pass