Added text to explain the storyline better. Also fixed alignment issue with mean_sea_level, remove pandas warning by using where.
Added text to explain the storyline better. Also fixed alignment issue with mean_sea_level, remove pandas warning by using where.

Sandor-PRA/pandas_tutorial,jonathanrocher/pandas_tutorial,ajaykliyara/pandas_tutorial,linan7788626/pandas_tutorial,jonathanrocher/pandas_tutorial,Sandor-PRA/pandas_tutorial,linan7788626/pandas_tutorial,wateryhcho/pandas_tutorial,wateryhcho/pandas_tutorial,ajaykliyara/pandas_tutorial,ajaykliyara/pandas_tutorial,Sandor-PRA/pandas_tutorial,jonathanrocher/pandas_tutorial,linan7788626/pandas_tutorial,wateryhcho/pandas_tutorial