Add yangson tutorial and junos config snippet

[dgjustice]

@dbarrosop I hope this isn't too all-over-the-place. There are a lot of gotchas and rabbit holes along the way, but I hope this gives a decent overview of the internals. I am more than happy to adapt it as necessary.

[dbarrosop]

I think it's a very good tutorial, I also like the way you decided to use to illustrate it :)

Two minor comments:

1. Could you add a note in the beginning this is an advanced topic?
2. We should probably create a "howto" section in the docs and add this document there, can you do that? Otherwise, sphinx check fails with /ntc_rosetta/docs/tutorials/Rosetta-and-Yangson-walkthrough.ipynb:document isn't included in any toctree

Thanks!

[jabelk]

I almost think we should split this up into two tutorials. Adding the junos example into the main flow and having the yangson into an advanced topics section

[dgjustice]

I kinda split the difference on your comments. I added an "advanced topics" warning, but left it alone otherwise. I then copy/pasta'd the IOS tutorials on merging and parsing with updates for Junos (the others are so similar by platform that I'm not sure it makes sense to break them out by driver at this point). Tests pass, so let me know if this is kosher or if you want more modifications.

[dbarrosop]

Let's merge it as I think there is value on getting it out there, we can iterate on it afterwards