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/develop/build_docker_image.mdx

@@ -1,6 +1,9 @@
 ---
 sidebar_position: 1
 slug: /build_docker_image
+sidebar_custom_props: {
+  categoryIcon: LucidePackage
+}
 ---
 
 # Build RAGFlow Docker image