添加注释

include/mutex/shared_mutex.h

@@ -37,6 +37,7 @@ namespace ling {
         shared_mutex &operator=(const shared_mutex &) = delete;
 
         void setResource(const T &&value) {
+            //改变持有的资源之前，先获得独占锁
             ResourceCompletely<T> lock_completely = lock();
             this->resource = value;
         }