Re: [PATCH v2 3/3] doc: add documentation for the hide-refs hook

> hook to filter the references during reference discovery phase.
>
> Signed-off-by: Sun Chao <sunchao9@huawei.com>
> ---
> diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
> @@ -249,6 +249,54 @@ If this hook exits with a non-zero status, `git push` will abort without
> +This hook would be invoked by 'git-receive-pack' and 'git-upload-pack'
> +during the reference discovery phase, each reference and will be filtered

> +by this hook. The hook executes once with no arguments for each
> +'git-upload-pack' and 'git-receive-pack' process. Once the hook is invoked,
> +a version number and server process name ('uploadpack' or 'receive') will
> +send to it in pkt-line format, followed by a flush-pkt. The hook should
> +response with its version number.

> +During reference discovery phase, each reference will be filtered by this
> +hook. In the following example, the letter 'G' stands for 'git-receive-pack'
> +or 'git-upload-pack' and the letter 'H' stands for this hook. The hook
> +decides if the reference will be hidden or not, it sends result back in
> +pkt-line format protocol, a response "hide" the references will hide
> +to the client and can not fetch it even in protocol V2.
> +
> +       # Version negotiation
> +       G: PKT-LINE(version=1\0uploadpack)
> +       G: flush-pkt
> +       H: PKT-LINE(version=1)
> +       H: flush-pkt
> +
> +       # Send reference filter request to hook
> +       G: PKT-LINE(ref <refname>:<refnamefull>)
> +       G: flush-pkt
> +
> +       # Receive result from the hook.
> +       # Case 1: this reference is hidden
> +       H: PKT-LINE(hide)
> +       H: flush-pkt
> +
> +       # Case 2: this reference can be advertised
> +       H: flush-pkt
> +
> +To enable the `hide-refs` hook, we should config hiderefs with `force:`
> +option, eg:
> +
> +       git config --add transfer.hiderefs force:refs/prefix1/
> +       git config --add uploadpack.hiderefs force:!refs/prefix2/
> +
> +the `hide-refs` will be called during reference discovery phase and
> +check each matched reference, a 'hide' reponse means the reference will