Add --classify to man page

contrib/man/exa.1

@@ -47,6 +47,11 @@ recurse into directories as a tree
 .RS
 .RE
 .TP
+.B \-F, \-\-classify
+display type indicator by file names
+.RS
+.RE
+.TP
 .B \-\-color, \-\-colour=\f[I]WHEN\f[]
 when to use terminal colours (always, automatic, never)
 .RS