Simplify Dokka configuration

[twyatt]

• Removed custom output folder for Dokka (leaning on defaults instead)
• Fixed some broken KDoc links

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Note

Low Risk
Documentation and CI packaging path only; no runtime or API behavior changes.

Overview
Dokka no longer overrides the HTML output directory in the root build.gradle.kts; GitHub Pages packaging now archives build/dokka/html instead of the old build/dokkaHtmlMultiModule path.

KDoc updates fix broken references: Android Connection docs now point at connectionScope (not scope), and Peripheral docs use [close] instead of a non-existent Peripheral.cancel, plus inline `requestMtu` instead of a bad [requestMtu] link. Unused cancel import removed from Peripheral.kt.

^{Reviewed by Cursor Bugbot for commit 53cb49d. Configure here.}