Readme.md updated to note that vs15.7 is needed

Author: eiximenis

README.md

@@ -1,5 +1,8 @@
 # eShopOnContainers - Microservices Architecture and Containers based Reference Application (**BETA state** - Visual Studio 2017 and CLI environments compatible)
-Sample .NET Core reference application, powered by Microsoft, based on a simplified microservices architecture and Docker containers. <p>
+Sample .NET Core reference application, powered by Microsoft, based on a simplified microservices architecture and Docker containers.
+
+## IMPORTANT NOTE!
+**Visual Studio 2017 15.7 Preview 2.0 or later is needed to run the solution** Due to the configuration used in `docker-compose.yml` file, VS15.7 (currently in Preview 2) is needed to run the solution. Trying to run the solution in VS15.6 (current RTM of Visual Studio 2017) will generate errors (complaining about invalid values in docker-compose file).
 
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