Improve example display in macro expander

Some variables allow to specify a <value> e.g. a time format string.

The default example tries to pass <value> to the exander, which most often is not a valid input. So some of the examples just give back <value>, but e.g. `CurrentTime:<value>` is expanded to `vpmlue`(or `vamlue`).

It would be better to give a concret example, like `CurrentTime:YYYY` which then exands to 2025