build.txt: Add compiler info.

nitrocaster · nitrocaster · commit 1a34390273e0 · 2016-01-14T14:23:57.000+03:00
diff --git a/doc/howto/build.txt b/doc/howto/build.txt
@@ -2,6 +2,8 @@ TITLE: X-Ray 1.6 build and setup instructions
 
 Build:
 ------
+Currently, the only compiler supported is Visual C++ 2015.
+
 By default, all libraries mentioned below (except Windows/DirectX SDK) are assumed to be in
 the src\Externals directory.
 
