updated user manual path

Author: jhansson-ard

content/hardware/_unlisted/boards/nano-matter/product.md

@@ -1,7 +1,7 @@
 ---
 title: Nano Matter
 url_shop: https://arduino.to/nano-matter
-primary_button_url: content\hardware\03.nano\boards\nano-matter\tutorials\user-manual
+primary_button_url: ./03.nano/boards/nano-matter/tutorials/user-manual
 primary_button_title: User Manual
 sku: [ABX00112]
 core: arduino:mbed_nano