fasta_sampler.nf : copy output to results

src/fasta_sampler.nf

 Channel
   .fromPath( "data/tiny_dataset/fasta/*.fasta" )
   .set { fasta_file }
+
 process sample_fasta {
+  publishDir "results/sampling/", mode: 'copy'
+  
   input:
 file fasta from fasta_file