document 'list' commands

[jacalata]

tabcmd list [projects|workbooks|datasources|flows] --details

-d, --details: print the generic item representation. If listing workbooks, also list all views in the workbook. (This can make a very long list).

Also, TODO

• add a count of items at the end of the list?

• 84

[jacalata]

Add some more detail to close this out https://github.com/tableau/tabcmd/pull/295