Added missing URL to .NET Foundation forums

Author: leecow

README.md

@@ -44,7 +44,7 @@ The [.NET Core Libraries][corefx] repo contains the base class libraries, which
 Engage, Contribute and Provide Feedback
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-Some of the best ways to contribute are to try things out, file bugs, and join in design conversations. You are encouraged to start a discussion by filing an issue, or starting a thread in the [.NET Foundation forums]. If you are having issues with the Full .NET Framework or .NET Runtime the best ways to file a bug are at [Connect](http://connect.microsoft.com/VisualStudio) or through [Product Support](https://support.microsoft.com/en-us/contactus?ws=support) if you have a contract.
+Some of the best ways to contribute are to try things out, file bugs, and join in design conversations. You are encouraged to start a discussion by filing an issue, or starting a thread in the [.NET Foundation forums](http://forums.dotnetfoundation.org/). If you are having issues with the Full .NET Framework or .NET Runtime the best ways to file a bug are at [Connect](http://connect.microsoft.com/VisualStudio) or through [Product Support](https://support.microsoft.com/en-us/contactus?ws=support) if you have a contract.
 
 Looking for something to work on? The list of [up-for-grabs issues](https://github.com/dotnet/coreclr/issues?q=is%3Aopen+is%3Aissue+label%3Aup-for-grabs) is a great place to start.