Add a "Translate this Doc" link to docs footer

[zeke]

At the bottom of each doc page, we have these links:

We should add another that says "Translate this Doc".

If the visitor's locale is the default English (US, Canadian, or otherwise), one of the following should happen:

a) link to Crowdin project landing page. This is very easy to implement but is not the best UX, as the person has to then pick a target language and re-navigate to the file in question:

b) display a modal (or a new page, or a <select> element) that prompts for desired target langauge, then redirects to the Crowdin page for that language/filename pair on Crowdin.

If the visitor's locale is not the default, clicking "Translate this Doc" should take them straight to their language/filename pair on Crowdin. 🎯

I've created a module get-crowdin-file-ids that we weave into the output of the electron-i18n module, so we generate these "straight to the right translation page" URLs from the website.

[zeke]

cc @pierreneter who is working on this.

[zeke]

I moved the get-crowdin-file-ids repo to the @electron org, made it work with the new electronjs.org crowdin proxy, and set up semantic releases for it.

@pierreneter this should unblock you. 🚀