feat: lessons 6, 7, 8 and 9 (#2)

Co-authored-by: yassine <yassine>

Author: tuxgopher

index.html

@@ -32,6 +32,10 @@
         <section data-markdown="lesson02.md" data-charset="utf-8"></section>
         <section data-markdown="lesson03.md" data-charset="utf-8"></section>
         <section data-markdown="lesson04.md" data-charset="utf-8"></section>
+        <section data-markdown="lesson05.md" data-charset="utf-8"></section>
+        <section data-markdown="lesson06.md" data-charset="utf-8"></section>
+        <section data-markdown="lesson07.md" data-charset="utf-8"></section>
+        <section data-markdown="lesson08.md" data-charset="utf-8"></section>
         <!-- NEW_SECTION_HERE -->
       </div>
     </div>