zcat: add -l example (#2823)

pages/common/zcat.md

@@ -5,3 +5,7 @@
 - Print the uncompressed contents of a gzipped file to the standard output:
 
 `zcat {{file.txt.gz}}`
+
+- Print compression details of a gzipped file to the standard output:
+
+`zcat -l {{file.txt.gz}}`