completes the processes md and adds the exercises

modules/qualifying/learning_processes.md

@@ -376,11 +376,27 @@ Why do you think this is?
 
 ### Renice
 
+Nice values are that practical if we need to set them before we start a process no?
+That's where the `renice` program comes into play.
+It allows us to change the nice value of a running process with a very simple syntax.
+I would advise you to use `sudo` when changing the nice values because otherwise you'll constantly run into either `operation not permitted` or `permission denied` errors.
 
+```
+➜  ~ git:(master) ✗ ping 8.8.8.8 > /dev/null &
+[1] 16877
+➜  ~ git:(master) ✗ ps o nice,pid,args -p 16877
+ NI   PID COMMAND
+  5 16877 ping 8.8.8.8
+➜  ~ git:(master) ✗ sudo renice -n 20 -p 16877
+16877 (process ID) old priority 5, new priority 19
+➜  ~ git:(master) ✗
+```
 
 ## Exercises
 
-Download the following files:
+To help you understand what happens to running and stopped processes I made a few python scripts you can download below.
+Run them either with `python3 $SCRIPT_NAME` or `./$SCRIPT_NAME`
 
-* f
+* [simple timer](./assets/processes_ex_01.py)
-* f
+* [timer with random keyboard prompt](./assets/processes_ex_02.py)
+* [custom callback function for SIGALRM](./assets/processes_ex_03.py)