Documentation improvements

[irm-codebase]

Improvements highlighted by @sjpfenninger and @brynpickering

• [x] A more thorough example on using a module in another workflow.
• [x] Include an example of each:
  • [x] geospatial gridded data (+ CRS metadata)
  • [x] geospatial polygon data (+ CRS metadata)
  • [x] Tabular data and how 'tidy' CSV files should look like.
  • [x] Configuration data (e.g., high level assumptions)
• [x] Move to longitude/latitude rather than x/y.
• [x] Clarify in the module IO how the {resolution}/{year} convention should work.