Update Data Library landing page

[jaxinewolfe]

This issue addresses documentation updates and improvements that could be made to the Data Library's landing page to make it more accessible (esp. for data contributors). For starters:

• Update README.md (sections to add: Getting started, How to contribute, Copywrite info, Funding and Acknowledgements, Related citations)
• Update CONTRIBUTING.md
• Create a gitbook (published via github pages) with extensive documentation about the database and how to contribute
• Add tags to the About section (right sidebar)
• Create a Milestone or Release for our Version 2.1.1 database

[jaxinewolfe]

Resources:

• A guide to using GitHub for developing and versioning data standards and reporting formats

Examples:

• NCEAS/eml landing page and associated github-pages
• ESS-DIVE Reporting Format for Soil Respiration guide and associated landing page
• Soils Data Harmonization & Synthesis website
• taxonomyCleanr

[jaxinewolfe]

More notes:
Potential tags: open-source, (meta)data-standard, data-synthesis, soil-carbon, biogeochemistry, carbon-sequestration-science

Contributing:

• Should contribution.md be split up into contributing data vs. contributing suggestions for our database?
• Should there be separate submission surveys for data contributions? (1) data that is already published and (2) data that the contributor would like CCN to publish. Or can we squeeze it all into one?
• For data releases, we should suggest that data contributors submit a metadata sheet with their data tables.
• Create issue templates for community suggestions (ex. Improve documentation, Add/revise variables or definitions, General)