[doc] emphasis on the existence of a tutorial
[doc] rephrasing, for the better
[doc] show that loading in redbaron is a one-liner

The example for the string is speratated from the file one because the
two together, the audience could think, at first glance, that RedBaron
needs a lot of statements to get started
[doc] rephrasing of the tree explanation
[doc] explain why is there a call to json module
[doc] explain that the root node is a list
[doc] explain methodically the help output
[doc] insert comment about pretty print in ipython
[doc] explain better the list node
[doc] more info on identifiers
[doc] don't only say it's the same, show it
[doc] let's stay modest and show room for improvement
[doc] fix example
[doc] enhance doc for proxy lists
Merge pull request #34 from Psycojoker/doc

Enhance tutorial before release