repo: use [--format=... | -z] instead of [-z] in git-repo-info synopsis

The flag -z is only an alias for --format=null and even though --format
and -z can be used together and repeated, only the last one is
considered.

Replace `[-z]` in the synopsis of git-repo-info by
`[--format=... | -z]`, expliciting that the use of one of those flags
replace the other.

Signed-off-by: Lucas Seiki Oshiro <lucasseikioshiro@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: lucasoshiro

Documentation/git-repo.adoc

@@ -8,7 +8,7 @@ git-repo - Retrieve information about the repository
 SYNOPSIS
 --------
 [synopsis]
-git repo info [--format=(keyvalue|nul)] [-z] [--all | <key>...]
+git repo info [--format=(keyvalue|nul) | -z] [--all | <key>...]
 git repo structure [--format=(table|keyvalue|nul)]
 
 DESCRIPTION
@@ -19,7 +19,7 @@ THIS COMMAND IS EXPERIMENTAL. THE BEHAVIOR MAY CHANGE.
 
 COMMANDS
 --------
-`info [--format=(keyvalue|nul)] [-z] [--all | <key>...]`::
+`info [--format=(keyvalue|nul) | -z] [--all | <key>...]`::
 	Retrieve metadata-related information about the current repository. Only
 	the requested data will be returned based on their keys (see "INFO KEYS"
 	section below).

builtin/repo.c

@@ -15,7 +15,7 @@
 #include "utf8.h"
 
 static const char *const repo_usage[] = {
-	"git repo info [--format=(keyvalue|nul)] [-z] [--all | <key>...]",
+	"git repo info [--format=(keyvalue|nul) | -z] [--all | <key>...]",
 	"git repo structure [--format=(table|keyvalue|nul)]",
 	NULL
 };