Add simple text example

http/hello_world.txt

@@ -1 +1,8 @@
 Hello World!
+If server were sending this as HTML, your browser wouldn't render this in its own line.
+Here are some translations. This file is encoded as UTF-8. Let's see if they look ok:
+   ¡Hola mundo!
+   שלום עולם
+   สวัสดีโลก!
+   أهلاً بالعالم
+

http/index.html

@@ -20,6 +20,7 @@
    <h3>Serve me some pages!</h3>
    <ul>
       <li><a href="index.html">Index</a>: This page (static)</li>
+      <li><a href="hello_world.txt">A text file</a>: Simple text, to verify MIME type is ok. (static)</li>
       <li><a href="cars.html">Nice cars</a>: Stress test, loads several "large" images. Makes the chip panic and restart :( (static)</li>
       <li><a href="zipped.html">Zipped</a>: File is actually saved as zipped.html.gz. A compressed file! (static but gzipped)</li>
       <li><a href="zipped.html.gz">Zipped</a>: Same exact file as served above. Server is smart enough to treat the .gz extension correctly (static but gzipped)</li>