.NET Framework Runtime and Builder Docker repos have merged

# .NET Framework Runtime and Builder Docker repos have merged

The [microsoft/dotnet-framework-build](https://hub.docker.com/r/microsoft/dotnet-framework-build/) Docker Hub repo has been merged into the [microsoft/dotnet-framework](https://hub.docker.com/r/microsoft/dotnet-framework/) Docker Hub repo. All new tags going forward will only be pushed to [microsoft/dotnet-framework](https://hub.docker.com/r/microsoft/dotnet-framework/). The images in the [microsoft/dotnet-framework-build](https://hub.docker.com/r/microsoft/dotnet-framework-build/) Docker Hub repo will be retained and serviced accordingly as to not affect existing usage.

## Discussion

Please share your thoughts on this change and see what others are saying at:

* [Microsoft/dotnet-framework-docker #125](https://github.com/Microsoft/dotnet-framework-docker/issues/125)

## Details

The [microsoft/dotnet-framework-build](https://hub.docker.com/r/microsoft/dotnet-framework-build/) Docker Hub repo has been merged into the [microsoft/dotnet-framework](https://hub.docker.com/r/microsoft/dotnet-framework/) Docker Hub repo.

* https://github.com/Microsoft/dotnet-framework-docker/pull/123
* https://github.com/Microsoft/dotnet-framework-docker/issues/78

In order to differentiate the runtime and build images, `runtime` and `sdk` distinguishing identifiers have been added to the tags. For example, `4.7.2-runtime` and `4.7.2-sdk`.

All new tags going forward will only be pushed to [microsoft/dotnet-framework](https://hub.docker.com/r/microsoft/dotnet-framework/). For example, the build images for 4.7.2 which was released today, only exist in [microsoft/dotnet-framework](https://hub.docker.com/r/microsoft/dotnet-framework/) repo.

The existing tags in [microsoft/dotnet-framework-build](https://hub.docker.com/r/microsoft/dotnet-framework-build/) will remain and be serviced accordingly. For example, the stable tags such as `4.7.1-windowsservercore-1709` will continue to be patched on a monthly basis.

We recommend that as you create and maintain your code, you move to use the new `runtime` and `sdk` images from the [microsoft/dotnet-framework](https://hub.docker.com/r/microsoft/dotnet-framework/) repo.

Start with pull request #123, issue #78, and the discussion in Microsoft/dotnet-framework-docker issue #125; the body provides no repository file or test entry point. The announcement describes a completed Docker Hub repository merge and does not define a remaining change or completion condition.

Written by the indexing model from the issue text.