Style Guide: first cell in notebooks should have all the imports

[MridulS]

No description provided.

[llorracc]

@MridulS please

1. Add this to the REMARKs README.md document
2. Make it so, for existing remarks.

[llorracc]

This should be true for DemARKs as well

There should be a uniform set of style guidelines that specify this

[llorracc]

This should really be in some "style guidelines" that we have not yet written.

For REMARKs, we should perhaps insist that the first cell EITHER import everything it needs OR just run the requirements.txt file (if one exists).

[sbenthall]

We now have this repository as an index to other repositories.

We can include 'Style guidelines' as a REMARK requirement, or not.

Shall they be mandatory?