added support for multiple columns in smiles_col,

created an example how the multiple columns work,
added gif to readme

Author: RokasEl

README.md

@@ -6,6 +6,7 @@
 
 ![Beautiful :)](https://raw.githubusercontent.com/wjm41/molplotly/main/images/color.gif)
 ![Beautiful :)](https://raw.githubusercontent.com/wjm41/molplotly/main/images/pca.gif)
+![Beautiful :)](https://raw.githubusercontent.com/wjm41/molplotly/main/images/multiple_smiles.gif)
 
 Required packages:
 - [rdkit](http://rdkit.org/docs/Install.html)