docs: document disabling native logs

[huytdps13400]

Summary

• replace the placeholder Logging guide with the supported iOS and Android build settings
• explain that disabling native logs removes noisy HybridObject lifecycle messages, including EntityWrapper churn during morph-target updates
• clarify that log control is build-time only and requires the native target to be regenerated

Closes #309.

Verification

• yarn --cwd docs typecheck
• yarn --cwd docs build
• yarn --cwd package check-all (ESLint and TypeScript passed; local clang-format is unavailable, and this PR changes no C++ files)
• git diff --check