v2archive: rewrite description for compression level option

> Rewrite the description of `-#` option. Since the option is also
> supported on tar archive, move to OPTIONS section and remove EXTRA.
>
> Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
> ---
>  Changes since v1 [1]:
>      - Mention common levels (store-only, fastest time, and best
>        compression).
>      - Note that compression level option is supported by both zip and
>        tar format, so move the description to OPTIONS section.
>
>  [1]: https://lore.kernel.org/git/xmqqpms6akup.fsf@gitster.g/T/#t
>
>  Documentation/git-archive.txt | 24 ++++++++----------------
>  1 file changed, 8 insertions(+), 16 deletions(-)
>
> diff --git a/Documentation/git-archive.txt b/Documentation/git-archive.txt
> index 9f8172828d..9aecc0936c 100644
> --- a/Documentation/git-archive.txt
> +++ b/Documentation/git-archive.txt
> @@ -9,7 +9,7 @@ git-archive - Create an archive of files from a named tree
>  SYNOPSIS
>  --------
>  [verse]
> -'git archive' [--format=<fmt>] [--list] [--prefix=<prefix>/] [<extra>]
> +'git archive' [--format=<fmt>] [--list] [--prefix=<prefix>/] [-#]
>  	      [-o <file> | --output=<file>] [--worktree-attributes]
>  	      [--remote=<repo> [--exec=<git-upload-archive>]] <tree-ish>
>  	      [<path>...]
> @@ -65,10 +65,6 @@ OPTIONS
>  	Look for attributes in .gitattributes files in the working tree
>  	as well (see <<ATTRIBUTES>>).
>  
> -<extra>::
> -	This can be any options that the archiver backend understands.
> -	See next section.
> -
>  --remote=<repo>::
>  	Instead of making a tar archive from the local repository,
>  	retrieve a tar archive from a remote repository. Note that the
> @@ -88,17 +84,13 @@ OPTIONS
>  	of the current working directory are included in the archive.
>  	If one or more paths are specified, only these are included.
>  
> -BACKEND EXTRA OPTIONS
> ----------------------
> -
> -zip
> -~~~
> --0::
> -	Store the files instead of deflating them.
> --9::
> -	Highest and slowest compression level.  You can specify any
> -	number from 1 to 9 to adjust compression speed and ratio.
> -
> +-#::
> +	Select the compression level. The supported levels and default
> +	value (if none is selected) are depending on compression command
> +	backend configured for the selected format (either explicitly with
> +	`--format` or inferred from file name specified with `-o`). Common
> +	values are `-0` for only storing files (zip only), `-1` for fastest
> +	compression time, and `-9` for best compression ratio.

>>  SYNOPSIS
>>  --------
>>  [verse]
>> -'git archive' [--format=<fmt>] [--list] [--prefix=<prefix>/] [<extra>]
>> +'git archive' [--format=<fmt>] [--list] [--prefix=<prefix>/] [-#]
>>  	      [-o <file> | --output=<file>] [--worktree-attributes]
>>  	      [--remote=<repo> [--exec=<git-upload-archive>]] <tree-ish>
>>  	      [<path>...]
>> @@ -65,10 +65,6 @@ OPTIONS
>>  	Look for attributes in .gitattributes files in the working tree
>>  	as well (see <<ATTRIBUTES>>).
>>  
>> -<extra>::
>> -	This can be any options that the archiver backend understands.
>> -	See next section.
>> -
>>  --remote=<repo>::
>>  	Instead of making a tar archive from the local repository,
>>  	retrieve a tar archive from a remote repository. Note that the
>> @@ -88,17 +84,13 @@ OPTIONS
>>  	of the current working directory are included in the archive.
>>  	If one or more paths are specified, only these are included.
>>  
>> -BACKEND EXTRA OPTIONS
>> ----------------------
>> -
>> -zip
>> -~~~
>> --0::
>> -	Store the files instead of deflating them.
>> --9::
>> -	Highest and slowest compression level.  You can specify any
>> -	number from 1 to 9 to adjust compression speed and ratio.
>> -
>> +-#::
>> +	Select the compression level. The supported levels and default
>> +	value (if none is selected) are depending on compression command
>> +	backend configured for the selected format (either explicitly with
>> +	`--format` or inferred from file name specified with `-o`). Common
>> +	values are `-0` for only storing files (zip only), `-1` for fastest
>> +	compression time, and `-9` for best compression ratio.
>
>
> This is getting there, but I think we really should not have a -# in the
> synopsis, since that's not how we refer to a digit-wildcard in any other
> context. And users might assume that a literal -# is meant, some
> commonly used tools even support that, e.g. try:
>
>     curl -L -o /dev/null -# https://cdimage.debian.org/debian-cd/current/amd64/iso-dvd/debian-11.1.0-amd64-DVD-1.iso
>
> Let's just use "[-<0..9 digit>[", or "[-<digit>]" in the SYNOPSIS and
> explain that it's 0..9 below in this section..

> I do not think it is a good idea to remove the backend-specific
> option section like this patch does, as the next archiver may not
> even support `-<digit>`.  Even with the existing two backends, the
> description of it need to be different (cf. the other response I
> sent you last night on "--fast/--best"?).  Rather, the first thing
> to improve would be to _add_ a section for `tar` format, next to the
> `zip` format, I would think, as those who wants to write `tar` do
> not have to read `zip` specific options, and vice versa.
> 
> The new paragraph on `-#` in the patch may work as a replacement for
> existing explanation for `zip`-specific extra options, but it needs
> to drop the changes made to make it applicable to any format, like
> "depending on ... backend" and "(zip only)" if we want to take it.