docs(android): drop stale interceptAction/removeActionInterceptor import

[kherembourg]

Summary

• Companion doc fix for Purchasely-Android-Sources#1627: interceptAction<T>/removeActionInterceptor<T> moved from top-level extension functions to inline members of Purchasely in SDK 6.0.0-rc.2+.
• Removes the now-stale import io.purchasely.ext.interceptAction / removeActionInterceptor from references/android/api-reference.md and references/android/migration-v6.md, and clarifies the JVM-11 notes in those files plus references/concepts/paywall-actions.md to say no separate import is needed.

Test plan

• Grepped repo for any remaining import io.purchasely.ext.interceptAction/removeActionInterceptor — none left
• CI green

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR updates Android docs for the v6 action interceptor imports.

• Removes stale interceptAction and removeActionInterceptor imports from Android examples.
• Clarifies that the reified helpers are inline members of Purchasely.
• Adds an Unreleased changelog entry for the documentation fix.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed documentation.
• The changelog entry follows the repository guidance for user-visible documentation changes.

Important Files Changed

Filename	Overview
CHANGELOG.md	Adds a concise Unreleased entry for the Android documentation import cleanup.
purchasely/references/android/api-reference.md	Removes stale top-level interceptor imports and updates the action interceptor note.
purchasely/references/android/migration-v6.md	Updates v6 migration guidance and removes the stale Kotlin interceptor import.
purchasely/references/concepts/paywall-actions.md	Clarifies that Android Kotlin action interceptors only need the Purchasely import.

_{Reviews (1): Last reviewed commit: "docs(android): drop stale interceptActio..." | Re-trigger Greptile}