docs: update French translation of index.mdx

[webdevbynight]

Summary

Updated index.mdx.

Refs: #1537, #1538, #1571

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Tracked Files

Locale	File	Note
fr	src/content/docs/index.mdx	Localization changed, will be marked as complete.

Warnings reference

Icon	Description
🔄️	The source for this localization has been updated since the creation of this pull request, make sure all changes in the source have been applied.