message: Fix windows build readme.
diff: @@ -84,6 +84,7 @@ Follow to https://http://zeromq.org/intro.
  - execute "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvars64.bat"
  - Point path to this directory using environment variables:
  - set INDY_PREBUILT_DEPS_DIR=C:\BIN\x64
  + - set INDY_CRYPTO_PREBUILT_DEPS_DIR=C:\BIN\x64
  - set MILAGRO_DIR=C:\BIN\x64
  - set LIBZMQ_PREFIX=C:\BIN\x64
  - set SODIUM_LIB_DIR=C:\BIN\x64
  