Improve step one of the notebook

[babakkhavari]

Fixed

• Explaining texts
• File downloads
• Added additional cells when needed.

Test it for bugs and make sure that the explaining text is correct

[camiloramirezgo]

When we make the release, we will need to remove the sys.path.append("..") line and the autoreloads. We will also need to update the paths as output_directory = '../example/results' I spect the behaviour to be that the user will be able to just download the example notebook, install onstove with conda and run the notebook directly being in the same directory. So the ../example won't be really required.

[camiloramirezgo]

I want to "hide" the data download steps into a function that gets called with the country as input only. We can put this function on a utils.py file in the example and import it. I think this will make the notebook cleaner and will avoid confusion among the participants about those download steps.

[camiloramirezgo]

Thing done:

• Reviewed and comlemented text
• Fixed one link to documentation that was wrong
• Added links to the sections in the description of the notebook
• Added links at the end of each section to be able to go back to the top of the notebook
• Rearrange order of the mask_all and aling_all methods
• Moved the description of each dataset to the section where it is read rather than at the begining of the data processing section
• Moved the DataProcessor creation to the data processing step, and left the definition of the output_directory to the begining of the notebook