docs: update docs icons (#12465)

### What problem does this PR solve?

Update icons for docs.
Trailing spaces are auto truncated by the editor, does not affect real
content.

### Type of change

- [x] Documentation Update

docs/guides/dataset/manage_metadata.md

@@ -1,6 +1,9 @@
 ---
 sidebar_position: -5
 slug: /manage_metadata
+sidebar_custom_props: {
+  categoryIcon: LucideCode
+}
 ---
 
 # Manage metadata
@@ -19,7 +22,7 @@ From v0.23.0 onwards, RAGFlow allows you to manage metadata both at the dataset
 ![](https://raw.githubusercontent.com/infiniflow/ragflow-docs/main/images/click_metadata.png)
 
 
-2. On the **Manage Metadata** page, you can do either of the following: 
+2. On the **Manage Metadata** page, you can do either of the following:
    - Edit Values: You can modify existing values. If you rename two values to be identical, they will be automatically merged.
    - Delete: You can delete specific values or entire fields. These changes will apply to all associated files.