added notes on how to install realsense camera

docu/notes_intel_realsense.txt

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+Installing Intel RealSense drivers:
+###################################
+echo 'deb http://realsense-hw-public.s3.amazonaws.com/Debian/apt-repo xenial main' || sudo tee /etc/apt/sources.list.d/realsense-public.list
+sudo add-apt-repository "deb http://realsense-hw-public.s3.amazonaws.com/Debian/apt-repo xenial main"
+sudo apt-get update
+sudo apt-get install librealsense2-dev
+sudo apt-get install librealsense2-dkms # enter a key for installing driver when asked (in my case the pw was realsense2019bt)
+sudo apt-get install librealsense2-utils
+
+Check if drivers were installed sucessfully:
+modinfo uvcvideo | grep "version:" # -> this should report the realsense camera driver
+
+
+# Installing the ROS package (assuming ros base is installed):
+Install dependencies:
+sudo apt-get install ros-kinetic-cv-bridge -y
+sudo apt-get install ros-kinetic-image-transport
+sudo apt-get install ros-kinetic-tf -y
+sudo apt-get install ros-kinetic-diagnostic-updater -y
+sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654
+sudo apt-get update
+sudo apt-get install ros-kinetic-ddynamic-reconfigure -y
+
+# clone github repo:
+git clone https://github.com/IntelRealSense/realsense-ros.git
+cd realsense-ros/
+git checkout `git tag | sort -V | grep -P "^\d+\.\d+\.\d+" | tail -1`
+mkdir -p ~/realsense_catkin_ws/src/realsense
+mv * ~/realsense_catkin_ws/src/realsense/
+
+cd ~/realsense_catkin_ws/src/
+catkin_init_workspace
+cd .. 
+catkin_make clean
+catkin_make -DCATKIN_ENABLE_TESTING=False -DCMAKE_BUILD_TYPE=Release
+catkin_make install
+echo "source ~/realsense_catkin_ws/devel/setup.bash" >> ~/.bashrc
+source ~/.bashrc
+
+Test with:
+roslaunch realsense2_camera rs_camera.launch
+
+Possible issue:
+The camera requires a USB 3 port to provide full resolution streams