Add guide on how to use the full meatadata spreadsheet

[NoopDog]

Need

Now that we have an Excel format full metadata spreadsheet downloadable from the data browser, it will be helpful to have a "Guide" explaining how to use it.

Approach

There is a wrangler document with information on the spreadsheet that can be adapted for the guide. The wrangling team will provide the document in a Google doc with images/text that can be converted to markdown and added to the site in the "Guides" section.