Add few install instructions

README.md

@@ -2,3 +2,14 @@ shuri
 =====
 
 Simple url shortener script
+
+Installation
+------------
+
+Just drop the `index.php` in any folder accessible through your web server with
+php interpreter, `mkdir db` with permission to write for your web server
+user/group and direct your browser to the former script.
+
+For testing and debugging purposer, you can just use:
+
+    $ php -S localhost:8000 index.php