Correct link for plato

As stated in the original repository's [readme][] it is moved to the new repository

[readme]:https://github.com/jsoverson/plato
Merge pull request #127 from dvberkel/master

Correct link for plato
Update it-IT

Added contributors and fixed links.
Merge pull request #132 from Ragnarokkr/update_it-IT

Update it-IT
clarifications on let and const
Merge pull request #135 from calvinmetcalf/patch-1

clarifications on let and const
Delete broken link

 * [Leveraging Code Quality Tools by Anton Kovalyov](http://anton.kovalyov.net/slides/gothamjs/)

Leads to 404 Error
Merge pull request #140 from bricejlin/patch-1

Delete broken link
Updated spanish translation + minor fixes
Merge pull request #142 from MatiasArriola/upstream

es-ES translation updated + minor fixes