...the current directory as the default the target directory
This seems like a good default and smooth the first contact with the
tool.
---
scan: start documenting the --output-format option better
This is still quite short, but already better. This leave room for
expanding the format list and the associated description.
---
output: add a "summary" output
This is a small and minimal output to display some information without
overwhelming the user with a wall of text.
Example output:
```
Files: 89
known: 40 ( 44%)
directories: 11
fully-known: 3 ( 27%)
partially-known: 0 ( 0%)
```
It can most probably be improved, but this can come later.
---
output: pick "summary" as the default
This should be less scary than "text" for a first contact.