doc: install example .cfg files to $(docdir)/examples/

Change-Id: I8671ce33b9bf28c89f767dd1b4a1463aeb275158
diff --git a/debian/osmo-hlr.install b/debian/osmo-hlr.install
index 0e2a1c4..1e3bbc6 100644
--- a/debian/osmo-hlr.install
+++ b/debian/osmo-hlr.install
@@ -1,3 +1,4 @@
 /usr/bin/osmo-hlr
 /usr/bin/osmo-hlr-db-tool
 /usr/share/doc/osmo-hlr/hlr.sql
+/usr/share/doc/osmo-hlr/examples/osmo-hlr.cfg