By default image is build with enabled autoupdate feature (take a look at tf.sh file).
You can create new Dockerfile based on that image (FROM tf2) and customize it with plugins, configs, CMD and ENTRYPOINT instructions.
# Build image and tag it as tf2
docker build -t tf2 github.com/Gonzih/docker-tf2-server
# Run image with default options (CMD in Dockerfile)
docker run -d -p 27015:27015/udp tf2
# Run image with custom options
docker run -d -p 27015:27015/udp tf2 +sv_pure 2 +map ctf_2fort.bsp +maxplayers 32
# Run image with custom config
docker run -d -p 27015:27015/udp -v ~/server.cfg:/home/tf2/hlserver/tf2/tf/cfg/server.cfg:ro tf2