Develop a form letter to send to authors of datasets we've decided not to include

[MattF-NSIDC]

Our form letter should be encouraging to authors to help motivate them to make changes to open/standardize their data to meet our minimum requirements.

We can:

• Link to GitHub issues containing discussion around their data / layer
• Mention our usership: We have XX,XXX downloads, and YYY newsletter subscribers who would be eager to see your data

[MattF-NSIDC]

Include form letter language for datasets that were rejected because of licensing issues.

[MattF-NSIDC]

A possible dataset to trigger our first form letter is the CALM sites dataset. This dataset has many formats, and it's none can be used as the source of truth because they sometimes conflict with each other and provide unique content. No one dataset is complete and correct.

See: #591 and #667

[MattF-NSIDC]

@twilamoon-science is starting to think about the "We considered your dataset" form letter and sending a few out.

[MattF-NSIDC]

We think this is a good candidate for one of these letters:

#667