Added logger ctor that accepts only name(empty logger)

include/spdlog/logger.h

@@ -31,19 +31,30 @@ namespace spdlog {
 class logger
 {
 public:
+    // Empty logger
+    logger(std::string name) :
+            name_(std::move(name)),
+            sinks_(){}
+
+    // Logger with range on sinks
     template<typename It>
     logger(std::string name, It begin, It end)
         : name_(std::move(name))
         , sinks_(begin, end)
     {}
 
+    // Logger with single sink
     logger(std::string name, sink_ptr single_sink)
         : logger(std::move(name), {std::move(single_sink)})
     {}
+
+    // Logger with sinks init list
     logger(std::string name, sinks_init_list sinks)
         : logger(std::move(name), sinks.begin(), sinks.end())
     {}
 
+
+
     virtual ~logger() = default;
 
     logger(const logger &) = delete;