guidance updates not reflected on website version

[dklinges9]

These are changes that I have made to docs/ccrcn_database_structure.csv but NOT to the posted online guidance. I held off on the changing the webpage version because I was told to wait until manager review/group feedback. Nothing too major however.

associated_publications

• bibliography_id
• study_type -> publication_type, which is more specific and compatible with .bib format

methods_level:

• site_id
• core_id (methods sometimes are different between sites/cores in a given study)

site_level:

• state
• watershed

[jaxinewolfe]

We now have a methods ID which is shared between the methods and depthseries tables. The associated publications table has also been updated as well (addressed in #64). At the site level, the geography assignment script defines country and administrative division, but not watershed. We'll let that lie for now.