Fix typo in README.md regarding CI job rules

Author: allnes

README.md

@@ -23,5 +23,5 @@ Coverage report is available [here](https://learning-process.github.io/ppc-2025-
 
 ### Rules for submissions:
 1. You are not supposed to trigger CI jobs by frequent updates of your pull request. First you should test you work locally with all the scripts (code style).
-    * Respect others time and don't slow down the job queue
+    * Respect others time and don't slow down the job queue.
 2. Carefully check if the program can hang.