Add docker container to run Berp

docker-berp/Dockerfile

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+# Builds a docker image used for building most projects in this repo. It's
+# used both by contributors and CI.
+#
+FROM mcr.microsoft.com/dotnet/sdk:6.0
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update \
+    && apt-get install --assume-yes \
+    locales
+
+RUN locale-gen en_US.UTF-8
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
+WORKDIR /app
+
+RUN apt-get update && apt-get --assume-yes upgrade
+
+# Create a cukebot user. Some tools (Bundler, npm publish) don't work properly
+# when run as root
+ENV USER=cukebot
+ENV UID=1000
+ENV GID=2000
+
+RUN addgroup --gid "$GID" "$USER" \
+    && adduser \
+    --disabled-password \
+    --gecos "" \
+    --ingroup "$USER" \
+    --uid "$UID" \
+    --shell /bin/bash \
+    "$USER"
+
+## Trigger first run experience by running arbitrary cmd to populate local package cache
+RUN dotnet --list-sdks
+
+USER $USER
+
+## As a user install node and npm via node version-manager
+WORKDIR /home/$USER
+
+# Install Berp (dotnet tool installs are user-global; not system global)
+RUN dotnet tool install --global Berp --version 1.4.0 \
+      && echo 'export PATH="$PATH:/home/cukebot/.dotnet/tools"' >> ~/.bashrc
+
+WORKDIR /app
+
+
+CMD ["/bin/bash"]

docker-berp/README.md

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+
+# Docker container to run Berp
+
+To use this container run from the root of the gherkin repository:
+
+```plain
+docker build -t berp-env docker-berp/ && docker run --rm -ti -v "$PWD:/app" berp-env
+```
+
+to start the container. The `/app` directory in the container corresponds to the
+repository root.
+
+
+From there, `berp` is installed in your `$PATH`, meaning you should be able to run
+
+```
+make generate
+```
+
+in the project root or in your language folder.