Syntaxnet spec file and Docker?

I’m trying to learn Synatxnet. I have it running through Docker. But I really dont know much about either program Synatxnet or Docker. On the Github Sytaxnet page it says

The SyntaxNet models are configured via a combination of run-time
flags (which are easy to change) and a text format TaskSpec protocol
buffer. The spec file used in the demo is in
syntaxnet/models/parsey_mcparseface/context.pbtxt.

How exactly do I find the spec file to edit it?

I compiled SyntaxNet in a Docker container using this Dockerfile.

FROM java:8

ENV SYNTAXNETDIR=/opt/tensorflow PATH=$PATH:/root/bin

RUN mkdir -p $SYNTAXNETDIR \
    && cd $SYNTAXNETDIR \
    && apt-get update \
    && apt-get install git zlib1g-dev file swig python2.7 python-dev python-pip -y \
    && pip install --upgrade pip \
    && pip install -U protobuf==3.0.0b2 \
    && pip install asciitree \
    && pip install numpy \
    && wget https://github.com/bazelbuild/bazel/releases/download/0.2.2b/bazel-0.2.2b-installer-linux-x86_64.sh \
    && chmod +x bazel-0.2.2b-installer-linux-x86_64.sh \
    && ./bazel-0.2.2b-installer-linux-x86_64.sh --user \
    && git clone --recursive https://github.com/tensorflow/models.git \
    && cd $SYNTAXNETDIR/models/syntaxnet/tensorflow \
    && echo "\n\n\n" | ./configure \
    && apt-get autoremove -y \
    && apt-get clean

RUN cd $SYNTAXNETDIR/models/syntaxnet \
    && bazel test --genrule_strategy=standalone syntaxnet/... util/utf8/...

WORKDIR $SYNTAXNETDIR/models/syntaxnet

CMD [ "sh", "-c", "echo 'Bob brought the pizza to Alice.' | syntaxnet/demo.sh" ]

# COMMANDS to build and run
# ===============================
# mkdir build && cp Dockerfile build/ && cd build
# docker build -t syntaxnet .
# docker run syntaxnet