docs : update filesystem usage guide
This patch adds the smartfs filesystem usage guide on
new board.
@@ -18,7 +18,7 @@ Don't call architecture codes from application directly. When protected build en
3. [How to add static library](HowToAddStaticLibrary.md)
## File System
-Will be updated
+1. [How to use SmartFS](HowToUseSmartFS.md)
## Network
1. How to use LWIP (will be updated)
