Update README.md

Author: gioagu

README.md

@@ -27,7 +27,7 @@ In particular, the **Layer Loader** offers following functionalities:
 - Support for CityGML enumerations and codelists
 - All layer geometries are 3D: they can be visualised both in 2D and in 3D (Please be aware that 3D visualisation in QGIS 3D map is still a bit unstable...).
 
-Further details, and a user guide, can be found in the \user_guide subfolder of the plugin installation directory (see file "[3DCityDB-Tools_UserGuide.pdf](user_guide/3DCityDB-Tools_UserGuide_0.8.3.pdf)").
+Further details, and a user guide, can be found in the \user_guide subfolder of the plugin installation directory (see file "[3DCityDB-Tools_UserGuide.pdf](user_guide/3DCityDB-Tools_UserGuide_0.8.4.pdf)").
 
 Some datasets for testing purposes are available, too, and are contained in the \test_datasets subfolder.