[shootout] add initial docs for revcomp v2 example
[shootout] add initial docs for revcomp v2 example

Quinny/perl6-examples,perl6/perl6-examples,shlomif/perl6-examples,shlomif/perl6-examples,perl6/perl6-examples,stmuk/perl6-examples,Quinny/perl6-examples,perl6/perl6-examples,Quinny/perl6-examples,stmuk/perl6-examples,Quinny/perl6-examples,shlomif/perl6-examples,perl6/perl6-examples,stmuk/perl6-examples,stmuk/perl6-examples,shlomif/perl6-examples,perl6/perl6-examples,stmuk/perl6-examples,shlomif/perl6-examples,Quinny/perl6-examples