Add support of `variable`
TagUI is a CLI tool for digital process automation (RPA)
- #241 - improve use of variables - `variable` instead of '+variable+'
- #227 - make ask step consistent on Windows and macOS / Linux
- #228 - make api step work in sub-scripts called using tagui step
- #223, #232, #233, #234, #236, #240 - various doc improvements
Minor updates and various documentation improvements. Introduce `variable` to denote use of variable where text is expected (updated sample flows). Backward compatible with old syntax '+variable+'.