file: add -k and -s

pages/common/file.md

@@ -9,3 +9,11 @@
 - Look inside a zipped file and determine the file type(s) inside
 
 `file -z {{foo.zip}}`
+
+- Allow file to work with special or device files.
+
+`file -s {{filename}}`
+
+- Don't stop at first file type match; keep going until the end of the file.
+
+`file -k {{filename}}`