ftw.3: FTW_CHDIR has no effect on the 'fpath' argument passed to fn()

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man3/ftw.3

@@ -224,6 +224,10 @@ If set, do a
 to each directory before handling its contents.
 This is useful if the program needs to perform some action
 in the directory in which \fIfpath\fP resides.
+(Specifying this flag has no effect on the pathname that is passed in the
+.I fpath
+argument of
+.IR fn .)
 .TP
 .B FTW_DEPTH
 If set, do a post-order traversal, that is, call \fIfn\fP() for