remove old build instructions

FossilOrigin-Name: 78517b94a81ceb17fe24195629db381b5f42cfdca3d31e4eaeec1fbaf0a9c158

doc/Building.md

@@ -1,33 +0,0 @@
-# Building RETRO
-
-## Unix (BSD, Linux, macOS, Cygwin)
-
-Requirements:
-
-- a generic shell in `/bin/sh`
-- standard unix tools (cp, rm, mv, cd)
-- a c compiler (as `cc`)
-- a standard libc and libm
-- a unix-style host
-
-You can either use `make` or just run `./build.sh` directly.
-
-The resulting files will be in the `bin` directory: `rre` and
-`repl`.
-
-RETRO is known to build out of the box on FreeBSD, macOS, and
-Linux. It'll also build fine under Cygwin if you are using a
-Windows system.
-
-## Windows
-
-Requirements:
-
-- .NET Framework
-
-Process:
-
-    %windir%\Microsoft.NET\Framework\v2.0.50727\csc.exe implementations\repl.cs
-
-Copy the resulting `repl.exe` and the `ngaImage` to the same directory
-and run the `repl.exe`