create tools/nsc/docker/README.md with instructions how to use it

Author: AnastaZIuk

docker/README.md

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+# NSC Docker Godbolt
+
+## Run NSC tool straight from build directory in compiler explorer docker container!
+
+Currently only Windows platform with target *x86_64* architecture is supported. Tested with Hyper-V isolation mode.
+
+### Requirements
+
+- [***Docker Desktop***](https://www.docker.com/products/docker-desktop/)
+
+### How To
+
+Switch to windows containers, configure CMake (recommended Visual Studio generator) & build `run-compiler-explorer` target. After the build completes type `localhost` in your browser.
+
+![Containers for Windows](https://user-images.githubusercontent.com/65064509/152947300-affca592-35a7-4e4c-a7fc-2055ce1ba528.png)
+