add fibonacci example and update gitignore

Author: bistcuite

Diff for: .gitignore

@@ -1 +1,11 @@
 .vscode/
+
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+*.test
+*.out
+vendor/
+go.work

Diff for: examples/fibonacci.krb

@@ -0,0 +1,9 @@
+fn fib(n){
+	if n <= 1 {
+		return n
+	} else {
+		return fib(n-1) + fib(n-2)
+	} 
+}
+
+println(fib(9))