Update the Visual Studio download URL.

README.WINDOWS

@@ -5,7 +5,7 @@ README for Windows (32- and 64-bit) platforms
 BZFlag uses Microsoft Visual C++ for its prebuilt binary releases and project
 files are provided for it. The current compiler used is Visual C++ 2017 (VC15).
 You can download Visual Studio Community 2017 for free from here:
-https://www.visualstudio.com/downloads/
+https://aka.ms/vs/15/release/vs_community.exe
 
 **Targets**
 There are a total of 4 build targets in the VC projects. There are targets
@@ -15,7 +15,6 @@ our current script. Also, there's no real performance advantage in having a
 64-bit BZFlag client as the game doesn't use much RAM.
 
 **Required Libraries**
-
 Various third-party libraries are needed, which are packaged in our
 bzflag-dependencies repository. Either grab a pre-built binary package from
 the releases section, or build the dependencies from source as described at
@@ -24,7 +23,7 @@ the root of the bzflag source directory, such that libraries and headers are in
 <bzflag source>/dependencies/windows-<configuration>-<architecture>.
   https://github.com/BZFlag-Dev/bzflag-dependencies
 
-NSIS 3.03 is needed to build an installer, which is built as part of a release
+NSIS is needed to build an installer, which is built as part of a release
 build.
   http://nsis.sourceforge.net/