update sdk document (#2374)

### What problem does this PR solve?

_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

sdk/python/ragflow/modules/document.py

@@ -0,0 +1,75 @@
+
+from .base import Base
+
+
+
+class Document(Base):
+    def __init__(self, rag, res_dict):
+        self.id = ""
+        self.name = ""
+        self.thumbnail = None
+        self.kb_id = None
+        self.parser_method = ""
+        self.parser_config = {"pages": [[1, 1000000]]}
+        self.source_type = "local"
+        self.type = ""
+        self.created_by = ""
+        self.size = 0
+        self.token_num = 0
+        self.chunk_num = 0
+        self.progress = 0.0
+        self.progress_msg = ""
+        self.process_begin_at = None
+        self.process_duration = 0.0
+        for k in list(res_dict.keys()):
+            if k not in self.__dict__:
+                res_dict.pop(k)
+        super().__init__(rag, res_dict)
+
+    def save(self) -> bool:
+        """
+        Save the document details to the server.
+        """
+        res = self.post('/doc/save',
+                        {"id": self.id, "name": self.name, "thumbnail": self.thumbnail, "kb_id": self.kb_id,
+                         "parser_id": self.parser_method, "parser_config": self.parser_config.to_json(),
+                         "source_type": self.source_type, "type": self.type, "created_by": self.created_by,
+                         "size": self.size, "token_num": self.token_num, "chunk_num": self.chunk_num,
+                         "progress": self.progress, "progress_msg": self.progress_msg,
+                         "process_begin_at": self.process_begin_at, "process_duation": self.process_duration
+                         })
+        res = res.json()
+        if res.get("retmsg") == "success":
+            return True
+        raise Exception(res["retmsg"])
+
+    def delete(self) -> bool:
+        """
+        Delete the document from the server.
+        """
+        res = self.rm('/doc/delete',
+                      {"doc_id": self.id})
+        res = res.json()
+        if res.get("retmsg") == "success":
+            return True
+        raise Exception(res["retmsg"])
+
+    def download(self) -> bytes:
+        """
+        Download the document content from the server using the Flask API.
+
+        :return: The downloaded document content in bytes.
+        """
+        # Construct the URL for the API request using the document ID and knowledge base ID
+        res = self.get(f"/doc/{self.kb_id}/documents/{self.id}",
+                       {"headers": self.rag.authorization_header, "id": self.id, "name": self.name, "stream": True})
+
+        # Check the response status code to ensure the request was successful
+        if res.status_code == 200:
+            # Return the document content as bytes
+            return res.content
+        else:
+            # Handle the error and raise an exception
+            raise Exception(
+                f"Failed to download document. Server responded with: {res.status_code}, {res.text}"
+            )