Simplify example instructions and fix broken examples

Also convert to AsciiDoc while we're at it.

examples/hello_world/README.asciidoc

@@ -0,0 +1,25 @@
+= Hello world example
+
+To try this example, you need GNU `make` and `git` in your PATH.
+
+To build and run the example, use the following command:
+
+[source,bash]
+$ make run
+
+Then point your browser to http://localhost:8080
+
+== Example output
+
+[source,bash]
+----
+$ curl -i http://localhost:8080
+HTTP/1.1 200 OK
+connection: keep-alive
+server: Cowboy
+date: Fri, 28 Sep 2012 04:10:25 GMT
+content-length: 12
+content-type: text/plain
+
+Hello world!
+----

examples/hello_world/README.md

@@ -1,33 +0,0 @@
-Hello world example
-===================
-
-To try this example, you need GNU `make` and `git` in your PATH.
-
-To build the example, run the following command:
-
-``` bash
-$ make
-```
-
-To start the release in the foreground:
-
-``` bash
-$ ./_rel/hello_world_example/bin/hello_world_example console
-```
-
-Then point your browser at [http://localhost:8080](http://localhost:8080).
-
-Example output
---------------
-
-``` bash
-$ curl -i http://localhost:8080
-HTTP/1.1 200 OK
-connection: keep-alive
-server: Cowboy
-date: Fri, 28 Sep 2012 04:10:25 GMT
-content-length: 12
-content-type: text/plain
-
-Hello world!
-```