webfs(4): document -d and -D flags

sys/man/4/webfs

@@ -4,6 +4,8 @@ webfs \- world wide web file system
 .SH SYNOPSIS
 .B webfs
 [
+.B -Dd
+] [
 .B -A
 .I useragent
 ] [
@@ -30,6 +32,11 @@ and, if
 .I service
 is specified, will post a service file descriptor in 
 .BR /srv/\fIservice .
+The
+.B -d
+flag enables general debug printing to standard error while the
+.B -D
+flag enables 9P debug prints.
 .PP
 If the environment variable
 .B httpproxy

sys/src/cmd/webfs/fs.c

@@ -781,7 +781,7 @@ Srv fs =
 void
 usage(void)
 {
-	fprint(2, "usage: %s [-D] [-A useragent] [-T timeout] [-m mtpt] [-s service]\n", argv0);
+	fprint(2, "usage: %s [-Dd] [-A useragent] [-T timeout] [-m mtpt] [-s service]\n", argv0);
 	exits("usage");
 }