distro BUGFIX missing devel package header (#363)

This file has to be present for successful CESNET/netopeer2 build (devel).
https://github.com/CESNET/netopeer2/blob/devel/CMakeModules/FindLibNETCONF2.cmake#L74
diff --git a/distro/pkg/deb/libnetconf2-dev.install b/distro/pkg/deb/libnetconf2-dev.install
index 74785f7..c8a621f 100644
--- a/distro/pkg/deb/libnetconf2-dev.install
+++ b/distro/pkg/deb/libnetconf2-dev.install
@@ -3,3 +3,4 @@
 usr/include/libnetconf2/*
 usr/include/nc_client.h
 usr/include/nc_server.h
+usr/include/nc_version.h