Fix Internationalization heading link to english

[mu-hun]

In Internationalization document, The Table of Content Link is muted to -.

This issue was reported from Japanese document (#646). You can reproduce from any language.

In React doucment, Internationalization heading is wrapped to english

The document in the link above is maintain with english:

## React Element의 타입 지정하기 {#specifying-the-react-element-type}

It seems good to unify the links in English. Because there is no permerlink for each language like ko.preactjs.org.

[developit]

@x86chi it's possible to permalink: https://preactjs.com/?lang=kr

[mu-hun]

From the next page, the lang query string will be hidden.

Navagate to "Differences to React" steps:

1. https://preactjs.com/?lang=ko
2. https://preactjs.com/guide/v10/differences-to-react

I think it is difficult to manually paste and share the query string.

[developit]

@x86chi That's a fair point, yep! I had originally gone with the disappearing querystring because we didn't want to assume shared links should point to the same language - that way someone can share a link to documentation and it will detect.

Out of curiosity - did the docs automatically show in Korean for you when you first visited the site? We try to detect your language based on navigator.languages, but it's imperfect. Maybe that could be improved too.

I just re-read your original description and you're totally right about the heading identifiers - we're using a regular expression to convert non-alphanumeric characters to - and it doesn't account for non-english characters at all. We can definitely fix that.

[mu-hun]

did the docs automatically show in Korean for you when you first visited the site?

It works fine in modern browsers.

I had originally gone with the disappearing querystring because we didn't want to assume shared links should point to the same language

From a permerlink perspective, it seemed more semantic to always use a query string.