examples/ubuntu/avahi_client: add daemon configuration hint in error message

Bug: 24204144
Change-Id: I33668e885dd2344da429f204b5d09c722b2a2ff0
Reviewed-on: https://weave-review.googlesource.com/1094
Reviewed-by: Vitaly Buka <vitalybuka@google.com>

libweave/examples/ubuntu/avahi_client.cc

diff --git a/libweave/examples/ubuntu/avahi_client.cc b/libweave/examples/ubuntu/avahi_client.cc
index a77e85f..31e5741 100644
--- a/libweave/examples/ubuntu/avahi_client.cc
+++ b/libweave/examples/ubuntu/avahi_client.cc
@@ -37,7 +37,8 @@
   avahi_threaded_poll_start(thread_pool_.get());
 
   group_.reset(avahi_entry_group_new(client_.get(), GroupCallback, nullptr));
-  CHECK(group_) << avahi_strerror(avahi_client_errno(client_.get()));
+  CHECK(group_) << avahi_strerror(avahi_client_errno(client_.get()))
+                << ". Check avahi-daemon configuration";
 }
 
 MdnsImpl::~MdnsImpl() {