Update doc/usage.rst

I'm new to http methods other than GET and POST and spent a good few minutes searching google for PUT DELETE... So I thought I'd separate them somehow in the docs

doc/usage.rst

@@ -100,7 +100,7 @@ A route pattern consists of:
   pattern can include variable parts and you are able to set RegExp
   requirements for them.
 
-* *Method*: One of the following HTTP methods: ``GET``, ``POST``, ``PUT``
+* *Method*: One of the following HTTP methods: ``GET``, ``POST``, ``PUT`` or 
   ``DELETE``. This describes the interaction with the resource. Commonly only
   ``GET`` and ``POST`` are used, but it is possible to use the others as well.