Update for PR #100: man and README should be in sync

nnn.1

@@ -199,7 +199,7 @@ with a '^' (caret) symbol.
 .Pp
 If
 .Nm
-is invoked as root the default filter will also match hidden files.
+is invoked as root or the environment variable \fBNNN_SHOW_HIDDEN\fR is set the default filter will also match hidden files.
 .Pp
 In the \fInavigate-as-you-type\fR mode directories are opened in filter mode,
 allowing continuous navigation. Works best with the \fBarrow keys\fR.