Replace NSIS with Qt IFW in the documentation

hugo/content/installation/building/windows/index.md

@@ -23,7 +23,8 @@ Download Qt from from the official website [qt.io](https://www.qt.io/download-op
 > Make sure to choose the open source version of Qt and download the online installer.
 
 Select the latest Qt version with long-time support (LTS) and open the sub tree.
-Only the 'MSVC 2019 64-bit' component is needed.
+To build BornAgain, only the 'MSVC 2019 64-bit' component is needed.
+Qt Installer Framework is required for creating the installer executable.
 
 Make a symbolic link to the directory corresponding to the current Qt version:
 if Qt 6.y.z installed in `C:\Qt\6.y.z`, then in Windows `cmd` (with administrative rights) execute:
@@ -42,11 +43,6 @@ Download the **Windows x64 Installer** from the official website [cmake.org/down
 Python and some Python modules must be installed, as described in
 [Python on Windows](/installation/py/win).
 
-#### NSIS (for packaging only)
-
-Download and install NSIS 3.03 from the [official website](https://nsis.sourceforge.io/Download).
-Add NSIS to the system `PATH`; see below.
-
 #### SWIG
 
 If you want to re-build the Python-API with SWIG, download and install SWIG