- update the existing new grid page to only include content about grib2
- added an entirely new, hidden, page for dealing with original grib product
- updated all "notes" and "warnings" with new admonition boxes
- restructured some of the sections and added helpful subsection titles
- added small new sections "Creating New Menu Item" and "Using wgrib2"
- removed the environment version dependencies for mkdocs and mkdocs-unidata (because I'm updating the mkdocs-unidata package as well right now)
- modified the mkdocs.yml file slightly to use new "nav" tag instead of "pages"
