Add example of Challenge and Solution

Author: ac812

docs/chapters/chapter_02.md

@@ -1,6 +1,15 @@
 ## 2.1 First subtopic
-Here you can eneter text and if you need to cite[@creative_commons_2022]
+Here you can enter text and if you need to cite[@creative_commons_2022]
+
+!!! example "Challenge 1"
+
+    This is an example of text of Challenge 1
+
+    ??? success "Solution"
+
+        This is an example solution for Challenge 1.
+
 
 ## 2.2 Second subtopic
 
-## 2.3 Third subtopic
+## 2.3 Third subtopic