[advent] add a small topic brainstorm

Author: perlpilot

misc/perl6advent-2015/topic-brainstorming

@@ -16,6 +16,7 @@
 - How do I take advantage of the iterator API?
 - How do I write my own iterators?
 - What's in Perl 6.0.0?
+- What's the difference between the language version and the compiler version?
 - Explain the naming convention 6.christmas?
 - How do I get my Perl 6 modules on CPAN?  How do I install them?
 - doc.perl6.org