docs(private-api): add docs for private-api

app/router/private/username.py

@@ -10,13 +10,27 @@ from sqlmodel import select
 from sqlmodel.ext.asyncio.session import AsyncSession
 
 
-@router.post("/rename", tags=["rename"])
+@router.post(
+    "/rename",
+    name="修改用户名",
+)
 async def user_rename(
-    user_id: int = Body(...),
-    new_name: str = Body(...),
+    user_id: int = Body(..., description="要修改名称的用户 ID"),
+    new_name: str = Body(..., description="新的用户名"),
     session: AsyncSession = Depends(get_db),
     # currentUser: User = Depends(get_current_user)
 ):
+    """修改用户名
+
+    为指定用户修改用户名，并将原用户名添加到历史用户名列表中
+
+    错误情况:
+    - 404: 找不到指定用户
+    - 409: 新用户名已被占用
+
+    返回:
+    - 成功: None
+    """
     current_user = (await session.exec(select(User).where(User.id == user_id))).first()
     if current_user is None:
         raise HTTPException(404, "User not found")