fix: Remove redundant section headers from features and installation documentation

Author: ptthanh02

docs/src/content/docs/features.md

@@ -3,8 +3,6 @@ title: Features Overview
 description: Comprehensive overview of SmartSpawner's professional features for optimal server performance.
 ---
 
-## Core Features
-
 SmartSpawner provides enterprise-grade spawner management with focus on performance, usability, and integration. Here are some of its key features:
 
 ### Intuitive GUI System

docs/src/content/docs/installation.md

@@ -3,8 +3,6 @@ title: Installation
 description: Complete installation guide for SmartSpawner - from requirements to configuration.
 ---
 
-## System Requirements
-
 Before installing SmartSpawner, ensure your server meets these requirements:
 
 | Requirement | Specification |
@@ -15,6 +13,10 @@ Before installing SmartSpawner, ensure your server meets these requirements:
 
 ## Download SmartSpawner
 
+<div style="text-align: center; margin: 2rem 0 1rem;">
+  <img src="https://github.com/user-attachments/assets/c976b6a9-537c-46ec-8efc-0e80cdd0840d" alt="SmartSpawner Banner" style="max-width: 100%; border-radius: 12px;" />
+</div>
+
 Choose your preferred download source:
 
 <div style="text-align: center; margin: 1.5rem 0;">