Improve description of pkg-config-multi-arch-wrong-dir tag

Another likely cause for this case is using debhelper 9 or newer (thus enabling
multi-arch paths by default) on a non multi-arched package.

Signed-off-by: Bastien ROUCARIÈS <roucaries.bastien+debian@gmail.com>
The usual cure is in this case to render your package multi-arch.
Add pedantic tag for uscan pgp verification

Add a pedantic check for lack of gpg signature in debian directory.
It will help debian from a security point of view.
Detect lack of upstream key in case of watch file signature checking.

Check for missing debian/upstream-signing-key.pgp

Signed-off-by: Bastien ROUCARIÈS <roucaries.bastien+debian@gmail.com>
Add a test for detecting lack of upstream key in case of watch file signature checking

Lintian tag should carry test. Add a test for debian-watch-file-pubkey-file-is-missing