patchDocumentation/BreakingChanges: announce removal of git-pack-redundant(1)

> The git-pack-redundant(1) command is already in the process of being
> phased out and dies unless the user passes the `--i-still-use-this` flag
> since 4406522b76 (pack-redundant: escalate deprecation warning to an
> error, 2023-03-23). We haven't heard any complaints, so let's announce
> the removal of this command in Git 3.0 in our breaking changes document.
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  Documentation/BreakingChanges.txt | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)

> diff --git a/Documentation/BreakingChanges.txt b/Documentation/BreakingChanges.txt
> index 0532bfcf7f9..2b64665694f 100644
> --- a/Documentation/BreakingChanges.txt
> +++ b/Documentation/BreakingChanges.txt
> @@ -115,6 +115,26 @@ info/grafts as outdated, 2014-03-05) and will be removed.
>  +
>  Cf. <20140304174806.GA11561@sigill.intra.peff.net>.
>  
> +* The git-pack-redundant(1) command can be used to remove redundant pack files.
> +  The subcommand is unusably slow and the reason why nobody reports it as a
> +  performance bug is suspected to be the absense of users. We have nominated
> +  the command for removal and have started to emit a user-visible warning in
> +  c3b58472be (pack-redundant: gauge the usage before proposing its removal,
> +  2020-08-25) whenever the command is executed.
> ++
> +So far there was a single complaint about somebody still using the command, but
> +that complaint did not cause us to reverse course. On the contrary, we have
> +doubled down on the deprecation and starting with 4406522b76 (pack-redundant:
> +escalate deprecation warning to an error, 2023-03-23), the command dies unless
> +the user passes the `--i-still-use-this` option.
> ++
> +There have not been any subsequent complaints, so this command will finally be
> +removed.
> ++
> +Cf. <xmqq1rjuz6n3.fsf_-_@gitster.c.googlers.com>,
> +    <CAKvOHKAFXQwt4D8yUCCkf_TQL79mYaJ=KAKhtpDNTvHJFuX1NA@mail.gmail.com>,
> +    <20230323204047.GA9290@coredump.intra.peff.net>,
> +
>  == Superseded features that will not be deprecated
>  
>  Some features have gained newer replacements that aim to improve the design in