Create script/makefile goal to update also newly added internationalized texts

[radomirbosak]

This should be documented as well.

This is already partially done in duden/locale/build.sh.

Follow the SO answer https://stackoverflow.com/a/53849905

how can i update the .pot, .po and .mo files using get text module in Linux?

Generate POT files from Python code using xgettext:

https://www.gnu.org/software/gettext/manual/html_node/xgettext-Invocation.html#xgettext-Invocation

Update existing PO files from new POT files using msgmerge:

https://www.gnu.org/software/gettext/manual/html_node/msgmerge-Invocation.html#msgmerge-Invocation

Compile PO files into MO files using msgfmt:

https://www.gnu.org/software/gettext/manual/html_node/msgfmt-Invocation.html#msgfmt-Invocation