Use prettier ASCII art for file trees
Use prettier ASCII art for file trees

Closes https://github.com/perl6/doc/issues/1793

Steal the characters from the stuff `tree` command prints.
Also use `:lang<text>` instead of `:skip-test`.

stmuk/doc,MasterDuke17/doc,tbrowder/doc,perl6/doc,dmaestro/doc,stmuk/doc,MasterDuke17/doc,dmaestro/doc,tbrowder/doc,tbrowder/doc,jonathanstowe/doc,tbrowder/doc,MasterDuke17/doc,perl6/doc,perl6/doc,jonathanstowe/doc,dmaestro/doc,dmaestro/doc,perl6/doc,jonathanstowe/doc,dmaestro/doc,MasterDuke17/doc,stmuk/doc,stmuk/doc,jonathanstowe/doc,perl6/doc,jonathanstowe/doc,stmuk/doc