Add ROS_LOCALHOST_ONLY comment to bashrc

[Tiryoh]

+ # export ROS_LOCALHOST_ONLY=1

[Tiryoh]

ROS 2 Iron uses ROS_AUTOMATIC_DISCOVERY_RANGE instead of ROS_LOCALHOST_ONLY

https://docs.ros.org/en/iron/Releases/Release-Iron-Irwini.html#improved-discovery-options