Added Getting Started instructions for Docker for Windows

Docker for Windows is currently the recommended download for Windows. Running WebODM under Docker for Windows requires some extra steps setting up the Docker environment.

README.md

@@ -36,14 +36,16 @@ A free, user-friendly, extendable application and [API](http://docs.webodm.org)
  - [Python](https://www.python.org/downloads/)
  - [Git](https://git-scm.com/downloads)
 
-* From the Docker Quickstart Terminal (Windows) or from the command line (Mac / Linux) type:
+* Windows users have a choice between Docker Toolbox (older product but more tutorials available) and Docker for Windows (more recent version that runs on Microsoft's Hyper-V virtualization engine, recommended by Docker). Docker for Windows users should set up their Docker environment before launching WebODM using the Docker utility in the system tray: 1) make sure Linux containers are enabled (Switch to Linux Containers...), 2) give Docker enough CPUs (default 2) and RAM (>4Gb, 16Gb better but leave some for Windows) by going to Settings -- Advanced, and 3) select where on your hard drive you want virtual hard drives to reside (Settings -- Advanced -- Images & Volumes) . 
+
+* From the Docker Quickstart Terminal or Powershell (Windows), or from the command line (Mac / Linux), type:
 ```bash
 git clone https://github.com/OpenDroneMap/WebODM --config core.autocrlf=input
 cd WebODM
 ./webodm.sh start
 ```
 
-* If you're on Windows find the IP of your Docker machine by running this command from your Docker Quickstart Terminal:
+* If using Docker for Windows, open a browser and go to `http://localhost:8000/`. Docker Toolbox users can find the IP of your Docker machine by running this command from your Docker Quickstart Terminal:
 
 ```bash
 docker-machine ip