docs(aicore-ax-m1/download): add Hardware Design section with 3D model download link

Reference format from Dragon Q8B download page.

- 3D model: https://dl.radxa.com/aicore/ax_m1/radxa_aicore_ax_m1_3d_stp.zip

Author: tangzz-radxa

docs/aicore/ax-m1/download.md

@@ -18,5 +18,9 @@ sidebar_position: 15
 
 ## 参考文档
 
-- [Radxa 智核 AX-M1 产品规格书（英文）](https://dl.radxa.com/aicore/ax_m1/radxa_aicore_ax_m1_product_brief_en.pdf)
-- [Radxa 智核 AX-M1 产品规格书（中文）](https://dl.radxa.com/aicore/ax_m1/radxa_aicore_ax_m1_product_brief_zh.pdf)
+- [瑞莎智核 AX-M1 产品规格书（英文）](https://dl.radxa.com/aicore/ax_m1/radxa_aicore_ax_m1_product_brief_en.pdf)
+- [瑞莎智核 AX-M1 产品规格书（中文）](https://dl.radxa.com/aicore/ax_m1/radxa_aicore_ax_m1_product_brief_zh.pdf)
+
+## 硬件设计
+
+- [瑞莎智核 AX-M1 3D 模型](https://dl.radxa.com/aicore/ax_m1/radxa_aicore_ax_m1_3d_stp.zip)

i18n/en/docusaurus-plugin-content-docs/current/aicore/ax-m1/download.md

@@ -20,3 +20,7 @@ sidebar_position: 15
 
 - [Radxa AICore AX-M1 product brief (English)](https://dl.radxa.com/aicore/ax_m1/radxa_aicore_ax_m1_product_brief_en.pdf)
 - [Radxa AICore AX-M1 product brief (Chinese)](https://dl.radxa.com/aicore/ax_m1/radxa_aicore_ax_m1_product_brief_zh.pdf)
+
+## Hardware design
+
+- [Radxa AICore AX-M1 3D model](https://dl.radxa.com/aicore/ax_m1/radxa_aicore_ax_m1_3d_stp.zip)