debian/*.doc-base: Add .doc-base files for bin:packages containing documentation.

debian/libxcomp3.doc-base

+Document: libxcomp3
+Title: NX compression library
+Section: Screen
+
+Format: Text
+Files: /usr/share/doc/libxcomp3/README.on-retroactive-DXPC-license.gz
+
+Format: PDF
+Files: /usr/share/doc/libxcomp3/nxcomp-3.6-drops-compat-code-3.4.x-testing.pdf.gz

debian/nxagent.doc-base

+Document: nxagent
+Title: nx-X11 Agent (Xserver)
+Section: Screen
+
+Format: Text
+Files: /usr/share/doc/nxagent/README.keystrokes.gz

debian/nxproxy.doc-base

+Document: nxproxy
+Title: NX compression tool
+Section: Screen
+
+Format: Text
+Files: /usr/share/doc/nxproxy/README-VALGRIND