Other sentence formatting (ros2#5031)

* Add second dot to abbreviations
* Remove some random periods
* Escape some periods
* Convert some links
* Add formatted block

Author: DLu

source/Tutorials/Miscellaneous/Building-Realtime-rt_preempt-kernel-for-ROS-2.rst

@@ -28,7 +28,7 @@ and switch into it with
 
    cd ~/kernel
 
-We can go with a browser to https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/ and see if the version is there.
+We can go with a browser to `this page <https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/>`_ and see if the version is there.
 You can download it from the site and move it manually from /Downloads to the /kernel folder, or download it using wget by right clicking the link using "copy link location".
 Example: