message: readme updates for dev env
  readme updates for dev env
diff: @@ -12,6 +12,16 @@ Our goal is to improve the performance and development agility of Symphony's des
  In order to achieve those goals Symphony is participating and working in close collaboration with the [Foundation Desktop Wrapper Working Group](https://symphonyoss.atlassian.net/wiki/display/WGDWAPI/Working+Group+-+Desktop+Wrapper+API)
  +## Windows Dev Env
  +- For screen-snippet to work:
  + * MSBuild.exe must be in path. MSBuild.exe is available by installing Visual Studio 2017 Community.
  + * .NET3.5 SP1 must be installed.
  + * Note: screen-snippet is an optional dependency so if MSBuild.exe (Visual Studio) is not installed, then the install will still succeed, BUT the screen snippet functionality will not work on Windows.
  +- NodeJS version >= 7.4.0 (corresponds to electron 1.6.7) - needed to run tests locally
  +
  +## Mac Dev Env
  +- NodeJS version >= 7.4.0 (corresponds to electron 1.6.7) - needed to run tests locally
  +
  ## Run demo:
  - npm install
  - npm run demo-win (for windows)
  