[Documentation] Debian's lintian generates a lot of lintian warnings on manpages

**Describe the bug**
Debian's dropbox package is automatically linted, and it produces a lot of warnings:

https://udd.debian.org/lintian/?packages=distrobox

**To Reproduce**
- clone https://salsa.debian.org/michel/distrobox
- rebuild:
```
dpkg-source -b .
pbuilder-dist sid build ../distrobox*.dsc
lintian ~/pbuilder/sid_result/distrobox*_all.deb --tag-display-limit 0
```

**Expected behavior**
no `bad-whatis-entry` or `groff-message` warnings

**Logs**
Run the commands with `--verbose` and post the log here as a file upload
Attach also the output of `podman logs` or `docker logs`, possibly with `--latest` flag
[distrobox-lintian.txt](https://github.com/89luca89/distrobox/files/9235939/distrobox-lintian.txt)

**Desktop (please complete the following information):**
- Are you using podman or docker? N/A
- Which version or podman or docker? N/A
- Which version of distrobox? 1.3.1

**Additional context**
Add any other context about the problem here.