examples: show how to call a simple v module from ruby (#19073) (#19073)

This is a copy/adaptation of the python example (#13105)

examples/call_v_from_ruby/test.v

@@ -0,0 +1,13 @@
+module test
+
+import math
+
+[export: 'square']
+fn square(i int) int {
+	return i * i
+}
+
+[export: 'sqrt_of_sum_of_squares']
+fn sqrt_of_sum_of_squares(x f64, y f64) f64 {
+	return math.sqrt(x * x + y * y)
+}