doc: add exploding d6 example

01.workspace/oxidice_lib/examples/roll_exploding_d6.rs

@@ -0,0 +1,6 @@
+use oxidice_lib::dice::*;
+
+fn main(){
+    let roll = Handful::grab_exploding(1, 6, 6).roll();
+    println!("{roll}");
+}