Update 'README.md'

README.md

@@ -51,16 +51,7 @@ Initilize rosdep:
 	
 ## 2) PX4 Environment Development
 
-### Download PX4 source code
-	git clone https://github.com/PX4/PX4-Autopilot.git --recursive
-
-### Run ubuntu.sh
-	bash ./PX4-Autopilot/Tools/setup/ubuntu.sh
-	#Restart computer after it is done
-
-### Build ROS and Gazebo - This defaults to Gazebo9
-	wget https://raw.githubusercontent.com/PX4/Devguide/master/build_scripts/ubuntu_sim_ros_melodic.sh
-	bash ubuntu_sim_ros_melodic.sh
+Install [PX4 Firmware](https://docs.px4.io/main/en/dev_setup/dev_env_linux_ubuntu.html#rosgazebo). Then:
 
 #### Download QGroundControl from:
 	https://docs.qgroundcontrol.com/master/en/releases/daily_builds.html
@@ -124,16 +115,14 @@ In catkin_ws (or any working directory) add to devel/setup.bash:
 - First two elements can be changed to tweak tether parameters
 	- number_elements: number of segments tether will be composed of
 	- tl: segment length (should be no shorter than 0.3 meters)
-- __IMPORTANT:__ in order for jinja file to work, the following needs to be added to the _CMakeLists.txt_ (Ln 288 - may change in future) in the _~/PX4-Autopilot/Tools/sitl_gazebo_ folder:
-
+- __IMPORTANT:__ in order for jinja file to work, the following needs to be added to the _CMakeLists.txt_ in the _~/PX4-Autopilot/Tools/sitl_gazebo_ folder. This creates a custom command to build the tether file whenever a change is done to it. (Currently, it should be added after Ln 290 - may change in future)
 
 		COMMAND
 			${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/scripts/jinja_gen.py models/spiri_with_tether/spiri_with_tether.sdf} ${CMAKE_CURRENT_SOURCE_DIR}
 		DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/scripts/jinja_gen.py models/spiri_with_tether/spiri_with_tether.sdf
 		VERBATIM
-		)
-- This should be added in the line below VERBATIM in the add_custom_command function, which should be Ln 288)
 
+- This should be added in the line below VERBATIM in the add_custom_command function, which should be Ln 290). It should be part of the add_custom_command() after the 'else' statement
 
 ## ROS NODES
 ### LinkState.py