Simplify example instructions and fix broken examples

Also convert to AsciiDoc while we're at it.

examples/echo_get/README.asciidoc

@@ -1,29 +1,21 @@
-GET parameter echo example
-==========================
+= GET parameter echo example
 
 To try this example, you need GNU `make` and `git` in your PATH.
 
-To build the example, run the following command:
+To build and run the example, use the following command:
 
-``` bash
-$ make
-```
+[source,bash]
+$ make run
 
-To start the release in the foreground:
+Then point your browser to http://localhost:8080/?echo=hello
 
-``` bash
-$ ./_rel/echo_get_example/bin/echo_get_example console
-```
-
-Then point your browser at
-[http://localhost:8080/?echo=hello](http://localhost:8080/?echo=hello).
 You can replace the `echo` parameter with another to check
 that the handler is echoing it back properly.
 
-Example output
---------------
+== Example output
 
-``` bash
+[source,bash]
+----
 $ curl -i "http://localhost:8080/?echo=saymyname"
 HTTP/1.1 200 OK
 connection: keep-alive
@@ -33,4 +25,4 @@ content-length: 9
 content-type: text/plain; charset=utf-8
 
 saymyname
-```
+----