add perl6 code for chapters 1-4 (#49)

03_recursion/perl6/02_greet.p6

@@ -0,0 +1,19 @@
+#!/usr/bin/env perl6
+use v6.c;
+
+sub greet2($name) {
+    say "how are you, $name?";
+}
+
+sub bye() {
+    say "ok bye!";
+}
+
+sub greet($name) {
+    say "hello, $name!";
+    greet2 $name;
+    say "getting ready to say bye...";
+    bye;
+}
+
+greet "adit";