[virtual machine] added explanatory comment for load_snapshots_common…

… method.

src/platform/backends/shared/base_virtual_machine.h

@@ -87,6 +87,8 @@ class BaseVirtualMachine : public VirtualMachine
 private:
     using SnapshotMap = std::unordered_map<std::string, std::shared_ptr<Snapshot>>;
 
+    // the number of args is either 0 or 3, eventually this forwarding will lead to calling make_specific_snapshot
+    // with one filename argument or that one plus other three arguments.
     template <typename... Args>
     void load_snapshots_common(Args&&... args);
     template <typename LockT>