Option to add program description to the help text.

It would be nice to be able to add a more detailed program description to the help text. Like this.

```
Name: example
Description: runs example
Usage: example options_list
Arguments:
input -> Input file { String }
output -> Output file name (optional) { String }
```

No files or tests are named. Start by locating the help-text generation entry point and reviewing how the existing name, usage, and arguments are rendered; the work is done when a program description can be supplied and appears in help output in the requested format.

Written by the indexing model from the issue text.