Add example to README

Author: rgrinberg

README.md

@@ -3,6 +3,30 @@ ocaml-mustache
 
 mustache.js logic-less templates in OCaml
 
+
+Example usage
+-------------
+
+```ocaml
+let tmpl =
+  Mustache.of_string "Hello {{name}}\n\
+                      Mustache is:\n\
+                      {{#qualities}}\
+                      * {{name}}\n\
+                      {{/qualities}}"
+
+let json =
+  `O [ "name", `String "OCaml"
+     ; "qualities", `A [ `O ["name", `String "awesome"]
+                       ; `O ["name", `String "simple"]
+                       ; `O ["name", `String "fun"]
+                       ]
+     ]
+
+let rendered =
+  Mustache.render tmpl json
+```
+
 Todo/Wish List
 -----------
 * Support for ropes