Update README.md

Author: dennisbakhuis

B_Pandas_tips/README.md

@@ -14,4 +14,5 @@ Various notebooks demostrating nifty Pandas tricks
 [7. Give aggregation a name](https://github.com/dennisbakhuis/Tutorials/blob/master/B_Pandas_tips/7%20-%20Give%20aggregation%20a%20name.ipynb)\
 [8. Exploding your DataFrames](https://github.com/dennisbakhuis/Tutorials/blob/master/B_Pandas_tips/8%20-%20Explode%20your%20DataFrames.ipynb)\
 [9. Loc or query?](https://github.com/dennisbakhuis/Tutorials/blob/master/B_Pandas_tips/9%20-%20Query%20or%20loc.ipynb)\
-[10. Filter your rows and columns](https://github.com/dennisbakhuis/Tutorials/blob/master/B_Pandas_tips/10%20-%20Filter%20your%20rows%20and%20columns.ipynb)
+[10. Filter your rows and columns](https://github.com/dennisbakhuis/Tutorials/blob/master/B_Pandas_tips/10%20-%20Filter%20your%20rows%20and%20columns.ipynb)\
+[11. count_values like a pro](https://github.com/dennisbakhuis/Tutorials/blob/master/B_Pandas_tips/11%20-%20value_counts%20like%20a%20pro.ipynb)