`R6` documentation

[jmbarbone]

We (I) have been pretty lazy with the documentation. These current docs are written just so roxygen doesn't complain.

• [ ] ensure R6 object methods match documentation for wrappers
  • There are some warnings for the R6 documentation that we might be able to ignore them
  • I don't want to copy over documentation but there may be some duplicated because of the wrappers
• [x] Simplify examples to mostly bare minimal
  • Enough to get a gist of the function
  • We can be a bit more creative with vignettes without bogging down the documentation
  • Examples are currently shown in wrapper functions only.
• [ ] Review formatting
• [x] Review @family tags (can probably group a few)
• [x] Maintain @return tags (for most R6 it will be "The wbWorkbook object"
• [ ] Consider simplify names
• [ ] Consider moving public fields to private