update index

index.md

@@ -2,14 +2,14 @@
 title: #  R for beginners
 ---
 
-# R for beginners
+# R for beginners (2022)
 
   1. [Introduction to R and RStudio](./session_1.html)
-  2. [introduction to Tidyverse](./session_2.html)
+  2. [Introduction to Tidyverse](./session_2.html)
   3. [Transformations with ggplot2](./session_3.html)
-  4. [data transformation](./session_4.html)
+  4. [Data transformation](./session_4.html)
   5. [Pipping and grouping](./session_5.html)
-  6. [tidydata](./session_6.html)
+  6. [Tidydata](./session_6.html)
   7. [String & RegExp](./session_7.html)
   8. [Factors](./session_8.html)