Help to package xdoctest

[Bo YU <tsu.yubo@gmail.com>]

Hi,

I am packaging the xdoctest to meet ubelt's[0] B-D.

Now I think it has a good shape in packaging[1], but I am not sure
about below warning:

```
W: python3-xdoctest: no-manual-page [usr/bin/xdoctest]
P: xdoctest source: very-long-line-length-in-source-file 563 > 512
[dev/outline.md:11]
X: python3-xdoctest: application-in-library-section python [usr/bin/xdoctest]
X: xdoctest source: debian-watch-does-not-check-openpgp-signature [debian/watch]
X: python3-xdoctest: library-package-name-for-application [usr/bin/xdoctest]

```
First, the executable program is placed in the /usr/bin directory, right?
In my understanding, Python modules should be put in
/usr/lib/python3/dist-packages/xdoctest. But it is ok for program
entry in /usr/bin also.

If so, I should add manpage for it.

Please help me to confirm it, TIA.

BR,
Bo

[0]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1026966
[1]: https://salsa.debian.org/python-team/packages/xdoctest/-/tree/debian/main/