Added NBTData support

src/main/kotlin/net/axay/kspigot/annotations/KSpigotAnnotations.kt

@@ -16,4 +16,16 @@ annotation class UnsafeImplementation
  * unstable and should be checked every time
  * with a version change.
  */
-annotation class NMS_1_16_1
+annotation class NMS_1_16_1
+
+/**
+ * This element uses [net.minecraft.server]
+ * in some way. Because of that, it is
+ * unstable and should be checked every time
+ * with a version change.
+ *
+ * This element uses some part of NMS
+ * which is more likely to stay the same
+ * over a long period of time.
+ */
+annotation class NMS_General