Translate new keyword argument paragraph

[stomar]

See commit 87bd19a.

Done:

• bg
• de
• es
• fr
• id
• it
• [ ] ja currently unavailable ( check Documentation page for ja http://www.ruby-lang.org/ja/documentation/ #176 for further info )
• ko
• pl
• pt
• tr
• zh_cn
• zh_tw

[chikamichi]

Done for 🇫🇷

[take]

i'll work on 🗾

[chenyukang]

there are many parts of zh_cn/documentation/ are out of date.
I will have some work on them.

[stomar]

@tkhr ja is kind of decoupled from the rest, I assume most of the content is or has been maintained by core team members directly. It probably needs a separate issue for discussion which parts should be "unified" with the en version.

[take]

@stomar i c, thx for the information :)

[take]

@stomar updated the PR description for ja. revert the diff if u dont like it :)

[crabonature]

Done for Polish.

[marocchino]

🇰🇷 does not have ruby-from-other-languages yet.

[JuanitoFatas]

Done for zh_tw.

[meisyal]

Done for id.

[edercosta]

@stomar done for pt
see pr #1631