Temporarily disable appdash from docker-compose

Until I read the doc and find how to limit the retention,
otherwise it just eats all my ram and cpu and things start to fall
apart.

PUBLISHED_FROM=eb33fb44736f07b992270689217aca4af70513ff

docs/dns-server.adoc

@@ -0,0 +1,71 @@
+=== DNS server
+
+Disabled by default; enable with `-DMG_ENABLE_DNS_SERVER`. 
+
+==== mg_dns_create_reply()
+
+[source,c]
+----
+struct mg_dns_reply mg_dns_create_reply(struct mbuf *io,
+                                        struct mg_dns_message *msg);
+----
+Create a DNS reply.
+
+The reply will be based on an existing query message `msg`.
+The query body will be appended to the output buffer.
+"reply + recursion allowed" will be added to the message flags and
+message's num_answers will be set to 0.
+
+Answer records can be appended with `mg_dns_send_reply` or by lower
+level function defined in the DNS API.
+
+In order to send the reply use `mg_dns_send_reply`.
+It's possible to use a connection's send buffer as reply buffers,
+and it will work for both UDP and TCP connections.
+
+Example:
+
+```c
+reply = mg_dns_create_reply(&nc->send_mbuf, msg);
+for (i = 0; i < msg->num_questions; i++) {
+  rr = &msg->questions[i];
+  if (rr->rtype == MG_DNS_A_RECORD) {
+    mg_dns_reply_record(&reply, rr, 3600, &dummy_ip_addr, 4);
+  }
+}
+mg_dns_send_reply(nc, &reply);
+``` 
+
+==== mg_dns_reply_record()
+
+[source,c]
+----
+int mg_dns_reply_record(struct mg_dns_reply *reply,
+                        struct mg_dns_resource_record *question,
+                        const char *name, int rtype, int ttl, const void *rdata,
+                        size_t rdata_len);
+----
+Append a DNS reply record to the IO buffer and to the DNS message.
+
+The message num_answers field will be incremented. It's caller's duty
+to ensure num_answers is propertly initialized.
+
+Returns -1 on error. 
+
+==== mg_dns_send_reply()
+
+[source,c]
+----
+void mg_dns_send_reply(struct mg_connection *nc, struct mg_dns_reply *r);
+----
+Send a DNS reply through a connection.
+
+The DNS data is stored in an IO buffer pointed by reply structure in `r`.
+This function mutates the content of that buffer in order to ensure that
+the DNS header reflects size and flags of the mssage, that might have been
+updated either with `mg_dns_reply_record` or by direct manipulation of
+`r->message`.
+
+Once sent, the IO buffer will be trimmed unless the reply IO buffer
+is the connection's send buffer and the connection is not in UDP mode. 
+