Getting Lagrangian Diags ready for the Parcels anniversary event

[VeckoTheGecko]

Some tasks need to be done in order for us to get Lagrangian Diags ready for the Parcels event on 1 Oct.

TODO:

• Jimena: Update the README to prominently link to the website and clear out the old stuff.
• Jimena: Go through the 3 notebooks in /Diagnostics - copy those and move to docs/tutorials
• Jimena: Move any shared functions in the tutorials to /Diagnostics/Functions
• Nick: Check that all the tutorials in the docs/tutorials folder works
• Nick: Set up CI so that these notebooks are tested and run. Investigate isolated environments for notebooks (if its viable - otherwise default to a single environment).
• Nick: Update /Diagnostics/Functions to be a proper locally unstalled package (though one that raises a warning when importing - telling users to copy paste the code rather than installing this as a package).
• Nick + Jimena: Update contributing/quickstart instructions
• Nick (low priority): See if we can remove ./Simulations/toy_data_01.nc (only committed nc file) from repo