New tutorial on builtin configs

[flothesof]

I created a very short tutorial covering loading ITER, WEST and JET configs, as discussed today.

[pep8speaks]

Hello @flothesof! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file examples/tutorials/tuto_plot_basic.py:

Line 5:80: E501 line too long (87 > 79 characters)

• In the file examples/tutorials/tuto_plot_gallery_fusion_machines.py:

Line 5:80: E501 line too long (94 > 79 characters)
Line 14:80: E501 line too long (101 > 79 characters)
Line 16:80: E501 line too long (104 > 79 characters)
Line 17:80: E501 line too long (109 > 79 characters)
Line 24:80: E501 line too long (93 > 79 characters)
Line 30:80: E501 line too long (110 > 79 characters)
Line 33:1: E402 module level import not at top of file
Line 38:18: W292 no newline at end of file

[Didou09]

Good for me :-)

[Didou09]

I think PEP8 will complain on line length, but it's no big deal

[lasofivec]

same comment as Didier.

[Didou09]

I think we can agree to be flexible on PEP8 'line too long' for tutorials because this will show up mostly in a html and not really in a IDE.
What do you think @lasofivec ?
I think we can merge this one
I'll issue a release alpha 4 afterwards

[lasofivec]

same comment as Didier.