Remove links to issues in old repositories

CONTRIBUTING.md

@@ -5,7 +5,7 @@ You can contribute to .NET Runtime with issues and PRs. Simply filing issues for
 
 ## Contribution "Bar"
 
-Project maintainers will merge changes that improve the product significantly and broadly and that align with the [.NET Core roadmap](https://github.com/dotnet/core/blob/master/roadmap.md).
+Project maintainers will merge changes that improve the product significantly and broadly and that align with the [.NET Roadmap](https://github.com/dotnet/core/blob/master/roadmap.md).
 
 Maintainers will not merge changes that have narrowly-defined benefits, due to compatibility risk. The .NET Core codebase is used by several Microsoft products (for example, ASP.NET Core, .NET Framework 4.x, Windows Universal Apps) to enable execution of managed code. Other companies are building products on top of .NET, too. We may revert changes if they are found to be breaking.
 
@@ -74,14 +74,6 @@ Note: It is OK to create your PR as "[WIP]" on the upstream repo before the impl
 
 The team marks the most straightforward issues as [up for grabs](https://github.com/dotnet/runtime/labels/up-for-grabs). This set of issues is the place to start if you are interested in contributing but new to the codebase.
 
-Some issues have not yet been migrated here from our "old" repos. You can find those here:
-
-[CoreFX up for grabs](https://github.com/dotnet/corefx/issues?q=is%3Aopen+is%3Aissue+label%3Aup-for-grabs)
-
-[CoreCLR up for grabs](https://github.com/dotnet/coreclr/issues?q=is%3Aopen+is%3Aissue+label%3Aup-for-grabs)
-
-Even for these issues, the pull request should go to this repo.
-
 ## Commit Messages
 
 Please format commit messages as follows (based on [A Note About Git Commit Messages](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html)):