Fix (Build): Combined Duplicated Article with an Incorrect Filname

[honmanyau]

Combined article about variables that was merged with #9015 with an incorrect name with the existing article about variables. Build was tested to be okay locally.

This is a trivial change so please feel free to mark it as invalid once closed/merged.

✅️ By submitting this PR, I have verified the following:

• [x] Added descriptive name to PR
  • Your PR should NOT be called Update index.md, since it does not help the maintainer understand what has been changed.
  • For example, if you create a Variables article inside the Python directory, the pull request title should be Python: add Variables article.
  • Additional PR title examples:
  • Git: edit Git Commit article
  • PHP: create PHP section and add Data Structures article
• [x] Reviewed necessary formatting guidelines in CONTRIBUTING.md.
• [x] No plagiarized, duplicate, or repetitive content that has been directly copied from another source.

[Asjas]

:+1: