I have downloaded the reference human genome hg38.tar.gz from John Hopkins website. I want to convert it to fasta file so I can build my index genome with HISAT2. Do you know how I should convert this .tar.gz to .fa ? When I open the .tar file, there are files as genome.1.ht2 (1Gb), genome.2.ht2 (0.7 Gb), do I still need to build the index? Or are these .ht2 files the indexed genome on which I can align my reads?