Broken README link

[CursedRock17]

Hey y'all as pointed out by this ros index issue the ROS 2 tutorial to the RT_PREEMPT kernel in the README links to a dead website. Instead of routing to index.ros.org it should go to docs.ros.org. Specifically this is the Jazzy docs link that should be used:
https://docs.ros.org/en/jazzy/Tutorials/Miscellaneous/Building-Realtime-rt_preempt-kernel-for-ROS-2.html

I currently don't have the bandwidth for this, but this seems to be a simple issue to solve, especially for a beginner.