adoc: add D-GSM chapter to osmohlr-usermanual

Change-Id: I392b5523870c2ef3267179160028d26f3f761b77
diff --git a/doc/examples/osmo-hlr-dgsm.cfg b/doc/examples/osmo-hlr-dgsm.cfg
new file mode 100644
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+++ b/doc/examples/osmo-hlr-dgsm.cfg
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+# OsmoHLR example configuration for Distributed GSM (mslookup)
+hlr
+ gsup
+  # For D-GSM roaming, osmo-hlr's GSUP must listen on a public IP:
+  bind ip 10.9.8.7
+  # Each HLR should identify with a distinct name
+  ipa-name hlr-23
+mslookup
+ # Bind mslookup mDNS server and client on default multicast address and port:
+ # 239.192.23.42 port 4266
+ mdns bind
+ # Tell the mslookup server in osmo-hlr which IP+ports to return when a
+ # remote voice call or SMS wants to deliver to a local subscriber:
+ server
+  # local osmo-sip-connector SIP port
+  service sip.voice at 10.9.8.7 5060
+  # local osmo-msc SMPP port
+  service smpp.sms at 10.9.8.7 2775
+  # experimental: SMS-over-GSUP: this HLR's GSUP port
+  service gsup.sms at 10.9.8.7 4222
+  # only required if different from above 'gsup'/'bind ip':
+  #service gsup.hlr at 10.9.8.7 4222