Update virus.md

Author: lauraluebbert

docs/src/en/virus.md

@@ -15,7 +15,7 @@ This module was written by [Ferdous Nasri](https://github.com/ferbsx).
 `virus`  
 Virus taxon name (e.g. 'Zika virus'), taxon ID (e.g. '2697049'), NCBI accession number (e.g. 'NC\_045512.2'), space-separated list of accessions (e.g. 'NC\_045512.2 MN908947.3 MT020781.1'), or path to a text file containing accession numbers (one per line) (e.g. 'path/to/text.txt').  
 Add `--is_accession` when passing an NCBI accession number. Add `--is_sars_cov2` or `is_alphainfluenza` for optimized download of SARS-CoV2 or Alphainfluenza sequences, respectively.  
-Use flag `--download_all_accessions` to apply filters without searching for a specific virus.
+Use flag `--download_all_accessions` to apply filters without searching for a specific virus.  
 
 **Optional arguments**   
 
@@ -115,7 +115,7 @@ Flag to indicate that the `virus` positional argument is an accession number, a
   - Text file path: `accessions.txt` (one accession per line)
 
 `--download_all_accessions`   
-Use this flag when applying filters without searching for a specific virus.    
+Use this flag when applying filters without searching for a specific virus (leave `virus` argument empty).     
 ⚠️ **WARNING**: If you do not specify additional filters, this flag downloads ALL available viral sequences from NCBI (entire Viruses taxonomy, taxon ID 10239). This is an extremely large dataset that can take many hours to download and require significant disk space. Use with caution and ensure you have adequate storage and bandwidth. When this flag is set, the `virus` argument is ignored.
 
 `--refseq_only`