Unable to compile the ROS Gazebo plugin example from the tutorial

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How do you call catkin_create_pkg to create a gazebo package? The tutorial assumes you've already created the package, and no previous tutorial goes over this. I tried adopting the CMakeLists.txt used in turtlebot_gazebo, which is simply:

cmake_minimum_required(VERSION 2.8.3)
project(myrobot_gazebo)
find_package(catkin REQUIRED)
catkin_package()

catkin_add_env_hooks(25.myrobot-gazebo SHELLS sh DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/env-hooks)

install(DIRECTORY launch
        DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION})

install(DIRECTORY maps
        DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION})

install(DIRECTORY worlds
        DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION})

but running catkin_make gave me this error:

CMake Error at /opt/ros/indigo/share/catkin/cmake/catkin_add_env_hooks.cmake:93 (message):
  catkin_add_env_hooks() could not find environment hook.  Either
  '/home/user/git/myrobot/myrobot_gazebo/env-hooks/25.myrobot-gazebo.sh',
  '/home/user/git/myrobot/myrobot_gazebo/env-hooks/25.myrobot-gazebo.sh.em',
  '/home/user/git/myrobot/myrobot_gazebo/env-hooks/25.myrobot-gazebo.sh.develspace.em'
  or
  '/home/user/git/myrobot/myrobot_gazebo/env-hooks/25.myrobot-gazebo.sh.in'
  must exist.
Call Stack (most recent call first):
  myrobot_gazebo/CMakeLists.txt:6 (catkin_add_env_hooks)

I'm assuming this means I'm not including some env-hook file, but that's not mentioned in the tutorial, and I can't find any documentation that explains what this does, so I don't want to just blindly add files without understanding their purpose. What's the correct way to construct a ROS Gazebo package?