CocoaPods Deprecation Notice for OpenTelemetry Swift

The OpenTelemetry Swift maintainers are deprecating CocoaPods support for `opentelemetry-swift` and `opentelemetry-swift-core` in favor of Swift Package Manager (SPM), which is now the preferred distribution method. This transition aims to reduce maintenance complexity and align with Apple's ecosystem standards, with official CocoaPods support scheduled to end on December 2, 2026. While existing integrations will continue to function, all future updates, bug fixes, and security patches will be exclusively available through SPM.