Added a guide on setting metadata (#4935)

### What problem does this PR solve?


### Type of change


- [x] Documentation Update

docs/guides/configure_knowledge_base/_category_.json

@@ -0,0 +1,8 @@
+{
+  "label": "Configure a knowledge base",
+  "position": 0,
+  "link": {
+    "type": "generated-index",
+    "description": "Guides on configuring a knowledge base."
+  }
+}

docs/guides/configure_knowledge_base/set_metadata.md

@@ -0,0 +1,22 @@
+---
+sidebar_position: 0
+slug: /set_metada
+---
+
+# Set metadata
+
+Add metadata to an uploaded file
+
+---
+
+On the **Dataset** page of your knowledge base, you can add metadata to any uploaded file. This approach enables you to 'tag' additional information like URL, author, and date, to an existing file or dataset. In an AI-powered chat, such information will be sent to the LLM with the retrieved chunks for content generation.
+
+For example, if you have a dataset of HTML files and want the LLM to cite the source URL when responding to your query, add a `"url"` parameter to each file's metadata.
+
+![Image](https://github.com/user-attachments/assets/78cb5035-e96c-43f9-82d7-8fef1b68c843)
+
+:::note TIP
+Ensure that your metadata is in JSON format; otherwise, your updates will not be applied.
+:::
+
+![Image](https://github.com/user-attachments/assets/379cf2c5-4e37-4b79-8aeb-53bf8e01d326)

docs/guides/develop/launch_ragflow_from_source.md

@@ -3,7 +3,7 @@ sidebar_position: 2
 slug: /launch_ragflow_from_source
 ---
 
-# Launch the RAGFlow Service from Source 
+# Launch a RAGFlow Service from Source
 
 A guide explaining how to set up a RAGFlow service from its source code. By following this guide, you'll be able to debug using the source code.