Add japanese translation

[tani]

I start to translate readme in this branch. I used po4a with docker for portability, and added 3 commands in package.json . After the merging this branch, we can maintain the translations by the following steps.

1. npm run po:docker creates docker image
2. npm run po:update updates .po file for gettext
3. npm run po:translate translates document

This request is work in progress. When we complete the translation, I'm going to send message to you.

[ckipp01]

Thanks a lot for starting the work on this @nzt. I'm really excited about it. I haven't used or heard of po4a before, so let me make sure I understand the workflow after reading through the docs 😬 . Please correct me if I don't have the right understanding of how this worked.

1. I'm assuming that you originally used po4a-gettextize to generate the pot file which is the ja.po file.
2. When I would update the readme.md file in the future, I'd then run yarn po:update which would update the ja.po file. The new sections would be marked as fuzzy.
3. Then either the new translation would be manually added or updated and fuzzy removed?
4. Then I'd run yarn po:translate to generate the readme_jp.md file?

Does that more or less seem right? The third step is the one I'm not 100% positive how it works. Also, locally when I try to do the yarn po:translate I'm unable to get the readme_jp.md to be created. Also after the initial yarn po:update I get a po/ja.po~ created, but didn't see reference of that in the docs?

Finally, I like the dockerfile for portability, but am curious the best workflow for ci. For example, if someone updates the readme, should they automatically be forced to run the yarn po:update before it passes the ci in github actions etc. Not stuff we need to answer now, just random thoughts.

Thanks again for starting this. Please let me know how I can support you at all in this process.

[tani]

Honestly, I have never translated any documents, that is, I don't know how po4a works.
However, As po4a showed warning too much untranslated messages, I first translate whole paragraphs and I second run po4a-translate and po4a-updatepo again. Then, I will answer your questions. Until to finish translation, give me a time please.

[ckipp01]

Since it's been a few months, I'm going to go ahead and close this. I really appreciate the effort you put into this. In the future if this is something you want to pick up or someone else wants to, this is great work they can start off of.