Update files of learn/curves for i18n.

[shibomb]

Update files of https://p5js.org/learn/curves.html for i18n.

Changes:

• curves.hbs now supports internationalization.
• The target strings were added to src/data/en.yml.
• Also, src/data/es.yml, hi.yml, ko.yml, and zh-Hans.yml were automatically generated by the Github action.
  No translations have been done for these, so they should be translated by translators of the respective languages like this:
  https://github.com/processing/p5.js-website/issues/1216

Please refer to the test results:

• English: https://p5-js-ja-jp.pages.dev/learn/curves
• Japanese: https://p5-js-ja-jp.pages.dev/ja/learn/curves

[limzykenneth]

Looks good. Thanks!

[shibomb]

Thanks for reviewing and merging!