Add two more examples to comb

Just to make the "chunking" ability more obvious to newcomers.

Author: trosel

doc/Type/Str.pod6

@@ -336,6 +336,8 @@ If no matcher is supplied, a list of characters in the string
 Examples:
 
     say "abc".comb.perl;                 # OUTPUT: «("a", "b", "c").Seq␤»
+    say 'abcdefghijk'.comb(3).perl       # OUTPUT: «("abc", "def", "ghi", "jk").Seq␤»
+    say 'abcdefghijk'.comb(3, 2).perl    # OUTPUT: «("abc", "def").Seq␤»
     say comb(/\w/, "a;b;c").perl;        # OUTPUT: «("a", "b", "c").Seq␤»
     say comb(/\N/, "a;b;c").perl;        # OUTPUT: «("a", ";", "b", ";", "c").Seq␤»
     say comb(/\w/, "a;b;c", 2).perl;     # OUTPUT: «("a", "b").Seq␤»