Makefile: build to './bin/neo-go.exe' on windows

'.exe' extension is needed to automatically run the binary on win.

Makefile

@@ -1,7 +1,12 @@
 BRANCH = "master"
 REPONAME = "neo-go"
 NETMODE ?= "privnet"
-BINARY = "./bin/neo-go"
+GOOS ?= $(shell go env GOOS)
+EXTENSION=
+ifeq ($(GOOS),windows)
+  EXTENSION=".exe"
+endif
+BINARY=./bin/neo-go$(EXTENSION)
 DESTDIR = ""
 SYSCONFIGDIR = "/etc"
 BINDIR = "/usr/bin"

README.md

@@ -56,6 +56,19 @@ make build
 
 The resulting binary is `bin/neo-go`.
 
+#### Building on Windows
+
+To build NeoGo on Windows platform we recommend you to install `make` from [MinGW
+package](https://osdn.net/projects/mingw/). Then you can build NeoGo with:
+
+```
+make build
+```
+
+The resulting binary is `bin/neo-go.exe`.
+
+We also recommend you to switch the Windows Firewall off for further NeoGo node run.
+
 ## Running a node
 
 A node needs to connect to some network, either local one (usually referred to