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/admin/_category_.json

@@ -4,5 +4,8 @@
   "link": {
     "type": "generated-index",
     "description": "RAGFlow administration"
+  },
+  "customProps": {
+    "categoryIcon": "LucideUserCog"
   }
 }

docs/guides/admin/admin_cli.md

@@ -1,6 +1,9 @@
 ---
 sidebar_position: 2
 slug: /admin_cli
+sidebar_custom_props: {
+  categoryIcon: LucideSquareTerminal
+}
 ---
 
 # Admin CLI
@@ -27,9 +30,9 @@ The RAGFlow Admin CLI is a command-line-based system administration tool that of
     The default password is admin.
 
     **Parameters:**
-    
+
     - -h: RAGFlow admin server host address
-    
+
     - -p: RAGFlow admin server port
 
 ## Default administrative account

docs/guides/admin/admin_service.md

@@ -1,6 +1,9 @@
 ---
 sidebar_position: 0
 slug: /admin_service
+sidebar_custom_props: {
+  categoryIcon: LucideActivity
+}
 ---
 
 
@@ -24,7 +27,7 @@ With its unified interface design, the Admin Service combines the convenience of
    python admin/server/admin_server.py
    ```
 
-   The service will start and listen for incoming connections from the CLI on the configured port. 
+   The service will start and listen for incoming connections from the CLI on the configured port.
 
 ### Using docker image
 

docs/guides/admin/admin_ui.md

@@ -1,6 +1,9 @@
 ---
 sidebar_position: 1
 slug: /admin_ui
+sidebar_custom_props: {
+  categoryIcon: LucidePalette
+}
 ---
 
 # Admin UI