Merge pull request #4030 from dumarchie/Windows-Build

Add Windows specific build instructions

CAVEATS.md

@@ -2,6 +2,26 @@
 
 ## Windows
 
+It should be possible to build Rakudo with either MinGW or MSVC. The
+[official releases](https://rakudo.org/downloads) are built using MSVC.
+
+### Building with MSVC
+
+To build with Visual Studio, select "Developer Command Prompt for VS"
+from the "Visual Studio" folder in the Start menu. At the prompt like
+
+```
+C:\Program Files (x86)\Microsoft Visual Studio\2019\Community>
+```
+
+enter `VC\Auxiliary\Build\vcvars64.bat` which should output:
+
+```
+[vcvarsall.bat] Environment initialized for: 'x64'
+```
+
+Now you can [build Rakudo](README.md#building-and-installing-rakudo).
+
 ### Spectest requirements
 
 You need a recent version of either Strawberry Perl or ActiveState Perl.

README.md

@@ -25,8 +25,8 @@ text file.
 
 [![Build Status](https://dev.azure.com/Rakudo/rakudo/_apis/build/status/rakudo.rakudo?branchName=master)](https://dev.azure.com/Rakudo/rakudo/_build/latest?definitionId=1&branchName=master) [![Build Status](https://circleci.com/gh/rakudo/rakudo.svg?style=shield)](https://circleci.com/gh/rakudo/rakudo)[![Build Status](https://travis-ci.org/rakudo/rakudo.svg?branch=master)](https://travis-ci.org/rakudo/rakudo) [![Build Status](https://ci.appveyor.com/api/projects/status/github/rakudo/rakudo?svg=true)](https://ci.appveyor.com/project/rakudo/rakudo/branch/master)
 
-See the `INSTALL.txt` file for detailed prerequisites and build and
-installation instructions.
+See the `INSTALL.md` file for detailed prerequisites and build and
+installation instructions. Check `CAVEATS.md` for platform specific notes.
 
 The general process for building is running `perl Configure.pl` with
 the desired configuration options (common options listed below), and