fix(doc): minor edits (#353)

* chaning location:setLocation to location: set

I believe this is how the v4 api is supposed to be used

* adding note about :params

I had a hard time locating this information, and I feel like it's pretty crucial when using a router.

README.md

@@ -363,9 +363,10 @@ entry point of the application also becomes a site map, making it easier to
 figure out how views relate to each other.
 
 Under the hood `choo` uses [sheet-router]. Internally the
-currently rendered route is kept in `state.location`. If you want to modify
+currently rendered route is kept in `state.location`. To access the route 
+`:params` you can use `state.location.params`. If you want to modify
 the location programmatically the `reducer` for the location can be called
-using `send('location:setLocation', { location: href })`. This will not work
+using `send('location:set', { location: href })`. This will not work
 from within namespaced `models`, and usage should preferably be kept to a
 minimum. Changing views all over the place tends to lead to messiness.