docs: make -f Makefile.doc (#1589)

Mechanical change; ran the above command.

man/coredns-dnstap.7

@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "COREDNS\-DNSTAP" "7" "February 2018" "CoreDNS" "CoreDNS plugins"
+.TH "COREDNS\-DNSTAP" "7" "March 2018" "CoreDNS" "CoreDNS plugins"
 .
 .SH "NAME"
 \fIdnstap\fR \- enable logging to dnstap
@@ -77,7 +77,7 @@ The following command listens on the given socket and decodes messages to stdout
 .
 .nf
 
-% dnstap \-u /tmp/dnstap\.sock
+$ dnstap \-u /tmp/dnstap\.sock
 .
 .fi
 .
@@ -90,7 +90,7 @@ The following command listens on the given socket and saves message payloads to
 .
 .nf
 
-% dnstap \-u /tmp/dnstap\.sock \-w /tmp/test\.dnstap
+$ dnstap \-u /tmp/dnstap\.sock \-w /tmp/test\.dnstap
 .
 .fi
 .
@@ -103,11 +103,37 @@ Listen for dnstap messages on port 6000\.
 .
 .nf
 
-% dnstap \-l 127\.0\.0\.1:6000
+$ dnstap \-l 127\.0\.0\.1:6000
 .
 .fi
 .
 .IP "" 0
 .
+.SH "USING DNSTAP IN YOUR PLUGIN"
+.
+.nf
+
+import (
+    "github\.com/coredns/coredns/plugin/dnstap"
+    "github\.com/coredns/coredns/plugin/dnstap/msg"
+)
+
+func (h Dnstap) ServeDNS(ctx context\.Context, w dns\.ResponseWriter, r *dns\.Msg) (int, error) {
+    // log client query to Dnstap
+    if t := dnstap\.TapperFromContext(ctx); t != nil {
+        b := msg\.New()\.Time(time\.Now())\.Addr(w\.RemoteAddr())
+        if t\.Pack() {
+            b\.Msg(r)
+        }
+        if m, err := b\.ToClientQuery(); err == nil {
+            t\.TapMessage(m)
+        }
+    }
+
+    // \.\.\.
+}
+.
+.fi
+.
 .SH "SEE ALSO"
 dnstap\.info \fIhttp://dnstap\.info\fR\.