message: docs: document output compression
diff: @@ -180,3 +180,23 @@ When processing of a sequence fails for various reasons, not all output files wi
  | Analysis results JSON | `--output-json` | yes |
  | Insertions CSV | `--output-insertions` | yes |
  | Errors CSV | `--output-errors` | yes |
  +
  +## Compression of output files and writing to standard output (stdout)
  +
  +If any of the output filenames ends with one of the supported file extensions: `gz`, `bz2`, `xz`, `zstd`, it will be transparently compressed. Low compression level is used (roughly corresponds to level "2" for most formats).
  +
  +If output filename is "-" then the output will be written uncompressed to standard output (stdout).
  +
  +If a custom compression or other form of post-processing is needed, then you could tell Nextclade/Nextalign to write to stdout and then pipe the stdout to another program. For example:
  +
  +```bash
  +xzcat input.fasta.xz |
  +nextalign run -r reference.fasta -m genemap.gff -o - |
  +xz -9 > aligned.slowly.but.heavily.compressed.fasta.xz
  +```
  +
  +```bash
  +xzcat *.fasta.xz |
  +nextclade run -D dataset/ --output-tsv=- |
  +process_nextclade_tsv_further > processed.tsv
  +```
  