Update doc/po4a.conf for recent doc changes.

[omasanori]

The .pot and .po files are also updated. Happy translation!

[omasanori]

#11364 must influence this PR, so I'll rebase and update again if #11364 has landed.

[alexcrichton]

This seems gargantuan, is there any way that we could generate files like this?

[omasanori]

@alexcrichton Executing po4a ... in mk/docs.mk manually after updating doc/po4a.conf works. (current dependencies around make docs-l10n seems somehow broken so you can't use make for it; I'll revisit here later)

[omasanori]

Note that po4a won't remove .pot & .po files which has no corresponding master documents automatically (for safety, of course), so we have to remove old ones manually for now.

[alexcrichton]

We generally don't include generated files in the repository, so how about removing all of the generated files and commenting at the top of po4a.conf how to generate the files?

[omasanori]

Thank you. I totally agree with you.

My plan:

1. ignoring *.pot files,
2. keeping *.po files since they may include translated content even though they are originally generated, and
3. adding notes for translators to doc/po4a.conf (and/or doc/README for translators who have no experience on po4a?)

Does it make sense? Please point it out if I overlooked something.

[alexcrichton]

That sounds like a good idea to me, but is there a way that we an keep just the translated content of the *.po files? I have very little knowledge about how this all works, just trying to cut down on the size of these files.

[adrientetar]

If the files we want to keep are on a specific folder; selectively ignoring them can be worked out.

[omasanori]

@alexcrichton Theorically, gettext-like tools can merge *.po files only with translated content and *.pot files (as usual when master content has been updated).

Thus, if we use any reduction tool that removes untranslated enrties from *.po files, we can hold translated content without untranslated one safely. However, I don't know such tool and it's common in projects using *.po to keep untranslated messages in *.po files.

@adridu59 Thank you. Surely file paths we treat here is simple enough to filter using the .gitignore file.

[omasanori]

Well, I've found msgattrib --translated must do the reduction well. I'll try it.
Thank you for your advice, @alexcrichton!

[omasanori]

Instead of rebasing and updating this huge PR, I'll make some separated PRs. #11427 is the first part.

[alexcrichton]

Sounds good to me! To keep the queue size down, I'm going to close this for now, but feel free to keep the PRs coming!