Add Docker build badge to README.md
Change-Id: I8577bed7294511896338ac5a6db397b0fd03ee0c
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</div>
-[](https://github.com/named-data/ndn-cxx/actions/workflows/ci.yml)
-[](https://github.com/named-data/ndn-cxx/actions/workflows/docs.yml)
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+[](https://github.com/named-data/ndn-cxx/actions/workflows/ci.yml)
+[](https://github.com/named-data/ndn-cxx/actions/workflows/docker.yml)
+[](https://github.com/named-data/ndn-cxx/actions/workflows/docs.yml)
**ndn-cxx** is a C++17 library implementing Named Data Networking (NDN) primitives
that can be used to write various NDN applications. The library is currently being