add manual pages in Debian incoming repos (for both the main archive and the ports archive)

[pabs3]

Please add support for importing manual pages from the Debian incoming repos. These are where packages from maintainers and buildds go before they reach the main archive. There are two such archives, one for the main archive and one for the ports archive. The advantage of doing this is that new manual pages become available sooner and for people who have the incoming repos in their apt sources, when they know about a manual page via apt-file they can easily view the manual page without having to install the package.

https://incoming.debian.org/debian-buildd/
https://incoming.ports.debian.org/buildd/