Add a better bgzip example command

Updates #216

pyfaidx/__init__.py

@@ -432,7 +432,7 @@ def __init__(self,
                         "Compressed FASTA is only supported in BGZF format. Use "
                         "the samtools bgzip utility (instead of gzip) to "
                         "compress your FASTA. "
-                        "For example: zcat file.fa.gz | samtools bgzip -c > file.fa.bgz"
+                        "For example: gunzip file.fa.gz; bgzip file.fa"
                     )
         elif self.filename.lower().endswith(('.bz2', '.zip')):
             raise UnsupportedCompressionFormat(