Fix link to customizing-gitea

[kodermho]

The link to customizing-gitea in the label documentation is broken. This PR should adjust the relative path to fix the link

[silverwind]

I wonder if there is a linter to catch these.

[silverwind]

@kodermho can you also fix the same link in docs/content/doc/usage/labels.zh-cn.md?

[silverwind]

Actually I think this may need this format:

[linkname]{{< relref "doc/administration/customizing-gitea.en-us.md" >}}

At least I see this relref format used in various docs files, but not consistently.

[delvh]

The problem is the explicit section label.
That's probably why it isn't a relref yet.
I initially wanted to note that as well, then I noticed.

[silverwind]

I wonder what's the point of these relref. Is this some custom processing that we do? I guess any decent markdown render should be able to produce correct links but I guess it has something to do with our nonstandard language suffixes.

[delvh]

AFAIK, it's a function we've gotten through Hugo, to render the links correctly.
For example, for relrefs we know at compile time if the link is correct.
For normal links, we can never be sure as they might point at an external URL outside our control.
But yes, that function also handles our localization suffixes.

[silverwind]

Ah, this is https://gohugo.io/functions/relref/, but we are not actually using it in the recommended way with two args.

For normal links, we can never be sure as they might point at an external URL outside our control.

Anything that starts with ./ can be statically analyzed and I think writing a linter for this "standard" format would be quite trivial actually.