docs: Style the command and its options in the synopsis

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Message-Id: <1452718226-25001-1-git-send-email-sitsofe@yahoo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/qemu-ga.texi b/qemu-ga.texi
index 536a9b5..0e53bf6 100644
--- a/qemu-ga.texi
+++ b/qemu-ga.texi
@@ -1,6 +1,6 @@
 @example
 @c man begin SYNOPSIS
-usage: qemu-ga [OPTIONS]
+@command{qemu-ga} [@var{OPTIONS}]
 @c man end
 @end example