Add Readme for building and packaging benchmarks

theodolite-benchmarks/README.md

+# Theodolite Benchmarks
+
+Theodolite comes with a set of 4 benchmarks for event-driven microservices, which are implemented with Kafka Streams
+and Apache Flink. The benchmarks are based on typical use cases for stream processing and named: UC1, UC2, UC3 and UC4.
+
+## Building and packaging the benchmarks
+
+All benchmarks can be built with:
+
+```sh
+./gradlew build
+```
+
+This produces `.tar` files in `<benchmark-impl>/build/distribution`, where `<benchmark-impl>` is for example
+`uc1-kstreams`.
+
+## Building Docker images of the benchmarks
+
+Each benchmark implementation directory contains a Dockerfile. To build an image (in this case of `uc1-kstreams`), run:
+
+```sh
+docker build -t theodolite-uc1-kstreams ./uc1-kstreams
+```