- Replace mentions of Perl 6 with Raku
(See https://github.com/perl6/problem-solving/blob/master/solutions/language/Path-to-Raku.md)
- Document's sections is now part of the resulting raku file
- The resulting Raku file can now be executed without runtime/compile-time
errors
- Some examples had minor updates or fixes
- Update links, extensions and commands.
