update documentation

[achubaty]

user documentation

• user workflow examples/vignettes;

developer documentation

• processing ClimateNA data and building datasets;
• how to add new climate data for e.g. new years;

[achubaty]

additional notes from my most recent round of development:

• terra writes .asc files using unix line-endings, so ClimateNA can't read them. they need to be read in and re-written with windows line-endings;
• ClimateNA v7.4.1 made an important change: "Climate variables with decimals are no longer converted to integers in raster format." This will need to be addressed downstream in the canCLimateData module (and possibly elsewhere). (I am using ClimateNA v7.4.2);

Also note:

• I'm not using the ClimateNAr package -- it's too simple a wrapper around the cmdline API, and is very fragile/error-prone. Manually invoking things to ensure inputs are checked properly (e.g., Windows paths specified correctly).
• The ClimateNAr package cmdline wrapper function writes geotiffs not .asc files. This is good for filesizes but would require downstream changes in our workflows. I am bypassing this function and manually writing .asc files for now.
• There is currently no public source repo for the ClimateNAr package, so I don't know how to contribute improvements.