added index of classes

index.md

+---
+author:
+- Orestis Malaspinas
+title: Cours de programmation séquentielle
+autoSectionLabels: true
+autoEqnLabels: true
+eqnPrefix: 
+  - "éq."
+  - "éqs."
+chapters: true
+numberSections: true
+chaptersDepth: 1
+sectionsDepth: 3
+lang: fr
+documentclass: book
+papersize: A4
+cref: false
+pandoc-numbering:
+  - category: exercice
+    listing: Liste des exercices
+urlcolor: blue
+corrige: false
+---
+
+# Cours de programmation séquentielle
+
+## Introduction [PDF](intro.pdf)
+
+## Base 1 [PDF](base_1.pdf)
\ No newline at end of file