Clarify and consolidate terms used to refer to fields in common core metadata schema

[philipashlock]

The documentation is not very clear or consistent about what the actual common core metadata schema field names are or the language used to label these field names.

On the schema.md page the tables that list the fields and their description have the following table headings: Field, Definition, JSON. I don't believe the "Field" actually refers to the field name. Instead "Field" appears to be a human readable label or title describing the actual machine readable field name. Here, the actual field name appears to use the table heading of "JSON" even though this is not specific to JSON and is used throughout the documentation and examples in non-JSON contexts (including CSV and RDF). In fact, the tables that give a more detailed description of each field (lower in this page under the heading "Further Metadata Field Guidance") use the table heading of "Field" to describe the actual field name that's otherwise labeled as "JSON" in the tables above.

Unless I'm missing something here, I would re-label the human readable titles used to describe the fields. They could instead be called "Title" or "Description" or they could even be incorporated into the "Definition" field and perhaps shown in bold. Then the "JSON" table heading should be renamed to "Field" and be the first left-most column in those tables.

This confusion extends to the metadata-resources.md page as well where it doesn't appear that the actual field names are listed anywhere, only their human readable versions.

[JoshData]

I had suggested getting rid of that column entirely in #77, but since no one agreed with me there I'm very +1 here!