Tutorial instructions refer to wrong branch names

[alex-quin-gabriel]

https://plansys2.github.io/tutorials/docs/simple_example.html#overview

Instructions:
git clone -b <ros2-distro>-devel https://github.com/IntelligentRoboticsLabs/ros2_planning_system_examples.git src

actual branches: rolling, humble, jazzy, kilted

A complicating issue maybe, is that there are still some branches named "*-devel" around.

This also affects the other tutorials.