Subcurrency Explanation
Added a small explanation for subcurrency.
# Subcurrency
+The following is a simple example of a subcurrency which implements a `mint` and `send` function for a token. This example does not use Fuel's native asset system (see: [Native Assets](../blockchain-development/native_assets.md)).
+
```sway
{{#include ../../../examples/subcurrency/src/main.sw:body}}
```
