Update index.md

[solo-nko]

sidesというプロパティについて細かい誤字を修正

Description:

Small typos when referencing the sides property.

Motivation:

Helps make sure the problem is clearly worded and doesn't confuse learners.

[mfuji09]

OKです。ありがとうございます。

[github-actions]

Preview URLs

• /ja/docs/Learn/JavaScript/Objects/Test_your_skills:_Object-oriented_JavaScript

Flaws (47)

URL: /ja/docs/Learn/JavaScript/Objects/Test_your_skills:_Object-oriented_JavaScript
Title: スキルテスト: オブジェクト指向 JavaScript
Flaw count: 47

• macros:
  • /ja/docs/Learn/MathML/First_steps does not exist but fell back to /en-US/docs/Learn/MathML/First_steps
  • /ja/docs/Learn/MathML/First_steps/Getting_started does not exist but fell back to /en-US/docs/Learn/MathML/First_steps/Getting_started
  • /ja/docs/Learn/MathML/First_steps/Three_famous_mathematical_formulas does not exist but fell back to /en-US/docs/Learn/MathML/First_steps/Three_famous_mathematical_formulas
  • /ja/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Main_features does not exist but fell back to /en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Main_features
  • /ja/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_events_state does not exist but fell back to /en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_events_state
  • and 42 more flaws omitted