docs: explain the order of output in the batched mode of git-cat-file(1)

The batched mode of git-cat-file(1) reads multiple objects from stdin
and prints their respective contents to stdout.
The order in which those objects are printed is not documented
and may not be immediately obvious to the user.
Document it.

Signed-off-by: ahmed akef <aemed.akef.1@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-cat-file.txt

@@ -270,9 +270,9 @@ BATCH OUTPUT
 ------------
 
 If `--batch` or `--batch-check` is given, `cat-file` will read objects
-from stdin, one per line, and print information about them. By default,
-the whole line is considered as an object, as if it were fed to
-linkgit:git-rev-parse[1].
+from stdin, one per line, and print information about them in the same
+order as they have been read. By default, the whole line is
+considered as an object, as if it were fed to linkgit:git-rev-parse[1].
 
 When `--batch-command` is given, `cat-file` will read commands from stdin,
 one per line, and print information based on the command given. With