chore: split example into lib and script

examples/sample/lib/syntax.ak

@@ -1,17 +1,10 @@
-use aiken/context.{ScriptContext}
+use aiken/builtins.{appendByteString}
 
-pub type Datum {
-  something: String,
+pub type Bool {
+  True
+  False
 }
 
-pub type Redeemer {
-  Buy
-  Sell
-}
-
-pub fn validate(datum: Datum, rdmr: Redeemer, ctx: ScriptContext) -> Bool {
-  when rdmr is {
-    Buy -> True
-    Sell -> datum.something == "Aiken"
-  }
+pub fn append(a: ByteArray, b: ByteArray) -> ByteArray {
+  appendByteString(a, b)
 }