build on Windows: fix link

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

@@ -59,10 +59,8 @@ Add NSIS to the system `PATH`; see below.
 
 If you want to re-build the Python-API with SWIG, download and install SWIG
 from the official website
-[swig.org/download.html](http://www.swig.org/download.html)
-
-Information can be found on
-[http://www.swig.org/Doc1.3/windows.html#Windows_installation]
+[swig.org/download.html](http://www.swig.org/download.html).
+Installation instructions are at http://www.swig.org/Doc4.1/windows.html.
 
 Unpack the ZIP file and add its folder to PATH (so e.g. `C:\swigwin-4.0.2`)