Add Debian packaging information

This allows (among others) to build rtl-sdr nightly packages
for a variety of distributions as part of the network:osmocom:nightly
builds

debian/rtl-sdr.manpages

@@ -0,0 +1,7 @@
+debian/rtl_adsb.1
+debian/rtl_eeprom.1
+debian/rtl_fm.1
+debian/rtl_power.1
+debian/rtl_sdr.1
+debian/rtl_tcp.1
+debian/rtl_test.1