lib/nbt: move a comment (yes, very important commit)

src/lib/nbt.hpp

@@ -112,9 +112,9 @@ namespace NBT {
             public:
                 End();
 
-                ErrorOrVoid serialize(std::vector<uint8_t>* rawData) override;
                 // This needs a separate serializer because
                 // END tags have a special header.
+                ErrorOrVoid serialize(std::vector<uint8_t>* rawData) override;
                 ErrorOrVoid serializeWithoutHeader(std::vector<uint8_t>* rawData) override;
         };