docs: update documentation files and rename setup guide

[gabrielbmoro]

Summary

Update README, restructure documentation index, and rename the setup guide from android.md to kotlin.md to reflect Kotlin Multiplatform support.

Changed Files

• README.md — link and description updates
• docs/available-commands.md — minor copy edits
• docs/index.md — restructured content
• docs/setup/android.md → docs/setup/kotlin.md — renamed and updated
• mkdocs.yml — updated nav reference

[github-actions]

🦙 MegaLinter status: ⚠️ WARNING

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ HTML	htmlhint	1		0	0	0.67s
⚠️ JAVASCRIPT	standard	2	2	1	0	2.43s
✅ KOTLIN	detekt	yes		no	no	3.59s
✅ MARKDOWN	markdown-table-formatter	26	7	0	0	0.49s
✅ YAML	prettier	15	7	0	0	0.9s

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