[pkg] Fix doc-base section
As pointed by Lintian, the “Apps” section is only used in menu,
not in doc-base. We can just remove it.
Document: cubicweb-doc
Title: CubicWeb Documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Programming
Format: HTML
Index: /usr/share/doc/python-cubicweb-documentation/html/index.html
Files: /usr/share/doc/python-cubicweb-documentation/html/*