[1.7.x] Fixed #23499 -- Error in built-in template tag "now" documentation

Backport of ab8248361e0a7b4fc7684eaaa5891e16b8562683 from master.
[1.7.x] Fixed #23491 -- Clarified tutorial 3.

Thanks diek for the suggestion.

Backport of 54fd84e432 from master
[1.7.x] Overhauled the Welsh formats.py file.

Backport of df7187d795 from master
[1.7.x] Fixed #23417 -- Completed locale formats for zh_CN, zh_Hans, zh_Hant and zh_TW.

Backport of 1ac32e76ac from master