[Localization] "Report a problem with a translation" page is outdated

We don't use Trac anymore and we should update how to report translation issues.

If you don't know how to find the string to fix, you can open a ticket on our Bugtracker, under the Community/Translations component.

Replace to:

under the Community/Localization repository

Before opening a ticket, see the currently open tickets for Translations because maybe it is already reported.

Link to localization repository.