ls-remote.txt: delete unsupported option

-u <exec> has never been supported, but it was mentioned since
0a2bb55 (git ls-remote: make usage string match manpage -
2008-11-11). Nobody has complained about it for seven years, it's
probably safe to say nobody cares. So let's remove "-u" in documents
instead of adding code to support it.

While at there, fix --upload-pack syntax too.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-ls-remote.txt

@@ -9,7 +9,7 @@ git-ls-remote - List references in a remote repository
 SYNOPSIS
 --------
 [verse]
-'git ls-remote' [--heads] [--tags]  [-u <exec> | --upload-pack <exec>]
+'git ls-remote' [--heads] [--tags]  [--upload-pack=<exec>]
 	      [--exit-code] <repository> [<refs>...]
 
 DESCRIPTION
@@ -29,7 +29,6 @@ OPTIONS
 	both, references stored in refs/heads and refs/tags are
 	displayed.
 
--u <exec>::
 --upload-pack=<exec>::
 	Specify the full path of 'git-upload-pack' on the remote
 	host. This allows listing references from repositories accessed via

builtin/ls-remote.c

@@ -4,7 +4,7 @@
 #include "remote.h"
 
 static const char ls_remote_usage[] =
-"git ls-remote [--heads] [--tags]  [-u <exec> | --upload-pack <exec>]\n"
+"git ls-remote [--heads] [--tags]  [--upload-pack=<exec>]\n"
 "                     [-q | --quiet] [--exit-code] [--get-url] [<repository> [<refs>...]]";
 
 /*