Add reference to Thonny's AST explorer

[Aivar Annamaa]

Thonny IDE (http://thonny.org) can visualize the AST of currently opened script (Main menu => View => AST).

I thought you may want to reference this possibility in greentreesnakes.

[Aivar Annamaa]

I can create a pull request, if it makes it easier for you

[Thomas Kluyver]

Thanks! Do you want to put it in the 'see also' box?

[Aivar Annamaa]

Yes, good idea!

[Aivar Annamaa]

Should I make the PR or are you making the addition yourself?

[Thomas Kluyver]

Go for it! :-)

[Thomas Kluyver]

Fixed by pull request #3