src/README: Update example app network diagram

The first example of an app network is not a little more suggestive of a
real application and also shows that links are directional.

src/README.md

@@ -89,13 +89,6 @@ For example: Move packets from input ports to output ports or to a
 network adapter.
 
 
-— Method **myapp:relink**
-
-*Optional*. React to a changes in input/output links (`app.input` and
-`app.output`). This method is called after a link reconfiguration but
-before the next packets are processed.
-
-
 — Method **myapp:reconfig** *arg*
 
 *Optional*. Reconfigure the app with a new *arg*. If this method is not

src/README.md.src

@@ -34,11 +34,21 @@ implement a specific interface, which is used by the Snabb Switch engine
 to organize an *App Network*.
 
     DIAGRAM: Network
-    +-------+            +-------+
-    |       |            |       |
-    | App 1 *------------* App 2 |
-    |       |   (Link)   |       |
-    +-------+            +-------+
+                   +---------+
+                   |         |
+                +->* Filter0 *--+
+                |  |         |  |
+                |  +---------+  |
+    +---+----+  |               |  +----+---+
+    |        *--+               +->*        |
+    |  NIC0  |                     |  NIC1  |
+    |        *<-+               +--*        |
+    +---+----+  |               |  +----+---+
+                |  +---------+  |
+                |  |         |  |
+                +--* Filter1 *<-+
+                   |         |
+                   +---------+
 
 Usually, a Snabb Switch design will create a series of apps, interconnect
 these in a desired way using *links* and finally pass the resulting app