Update Guide.md with code placement instructions

Added instructions for code placement in Guide.md.

Author: Wuang26

Toolbox-docs/Guide.md

@@ -514,7 +514,7 @@ const/4 v4, 0x0
 
     aput-object v2, v3, v4
 ```
-> add this code above the just found:
+> add this code below the just found:
 ```
 invoke-static {v3}, Lcom/android/internal/util/kaorios/ToolboxUtils;->KaoriosKeybox([Ljava/security/cert/Certificate;)[Ljava/security/cert/Certificate;