Perl 6 shebang should be recognized

[AlexDaniel]

Upstream nano has this in perl.nanorc:

header "^#!.*perl[-0-9._]*"

I think that's what is making it recognize most perl 6 scripts as perl5.

perl6.nanorc should recognize perl6 shebang, and FWIW perl5 nanorc should be tweaked if this is submitted upstream.

[hankache]

44b503f3d5d75407defc2a16bb8b76dc0ad4f980

[AlexDaniel]

Maybe also do v6\.[a-z] so that it's going to work even if we ramp up language releases?

[hankache]

abec35264ac2495ee2811176695c4df45784d0d8