How to load different files and manage your environment on the "How to session"

[marimeireles]

Create a how to session on environment management.
I see that a common question that arises between newbies is that if it's possible to load python files in the HTML file and how to do it. We should try to make it more clear.

[marimeireles]

Being worked on by @do-me here: #595 (comment)

[marimeireles]

I guess we have enough docs on it now with the improvements on py-config