Marked plog version of InitLogger() as deprecated

include/rtc/global.hpp

@@ -39,7 +39,9 @@ enum class LogLevel { // Don't change, it must match plog severity
 typedef std::function<void(LogLevel level, string message)> LogCallback;
 
 RTC_CPP_EXPORT void InitLogger(LogLevel level, LogCallback callback = nullptr);
+
 #ifdef PLOG_DEFAULT_INSTANCE_ID
+// Deprecated, kept for retro-compatibility
 RTC_CPP_EXPORT void InitLogger(plog::Severity severity, plog::IAppender *appender = nullptr);
 #endif