Add to quick start documentation: once you create a case, do not change the sandbox

[billsacks]

A seemingly unintuitive aspect of CESM/cime is that, once you have created a case from a particular directory, it is very important not to change the code checked out in that directory until you are completely done with your case. Is that documented somewhere? I don't see it in the quick start guide, and that seems like a good place to include a warning about this. Maybe we can have a section at the end like "Important points to bear in mind"?

[jedwards4b]

We should be able to check hashes and let the user know if the sandbox has changed.

[mvertens]

@jedwards4b, @billsacks - can either of you please add this as an issue. This is an important one to have in place. I think that the suggestion that @jedwards4b is proposing is a really good one.

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On Fri, Oct 11, 2019 at 10:49 AM jedwards4b ***@***.***> wrote: We should be able to check hashes and let the user know if the sandbox has changed. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#129?email_source=notifications&email_token=AB4XCE7QUOICPCATCI4TO4TQOC4BDA5CNFSM4I7Q6OZKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEBAXIZI#issuecomment-541160549>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB4XCE5KFAWSFX3FLHY3EGLQOC4BDANCNFSM4I7Q6OZA> .

[billsacks]

There is already an issue for this in cime, opened by @ekluzek - ESMCI/cime#2726. I still feel this should be documented somewhere, whether or not we do this checking in cime.