Translation overview and version tracking for codex

[timse201]

Mozilla's support page is very translator friendly. Think we should keep an eye on it to improve our codex.
At the moment:

1. we dont have any overview which articles are translated and which are not and which one needs an update

2. we have a version tracking system - but we dont show translators in an intuitive way which sentences have to be edited.

3. if an article could be outdated in one language we dont inform visitors about that

4. we dont have templates for phrases that are repeated oftenly

5. we have to edit site urls and language menu manually

mozilla's way:

1. & 2. ​https://support.mozilla.org/de/localization (sorry its an german page because en_Us is the main language) here you get an overview which articles are not translated yet or needs an update. If you click on 'Aktualisierung benötigt' (Update required) you see an github-based changeset and you can edit it directly

3. mozilla displays an information box in top of that page - after a while

4. yes but we could enhance it with sentences and words that are already translated via translate.wordpress.org and insert them automaticaly so that the translated version is always up to date

5. its done automaticaly

[timse201]

#3346 was marked as a duplicate.

[dd32]

I'm closing this ticket in favour of #658 as the Codex is deprecated in favour of HelpHub and DeveloperHub