improve workflow

* new workflow icon
* icons per result
* improve performance by querying prefix.cc only once
* change keyword from `ns` to `rdf`
* add screenshot to README

Author: Marvin Frommhold

README.md

@@ -2,11 +2,13 @@
 
 Lookup for namespaces using [prefix.cc](http://prefix.cc/).
 
+![Screenshot](screenshot.png)
+
 ## Usage
 
 When triggered, the workflow shows the RDF namespace for a given prefix. Additionally, it shows the prefix declaration for SPARQL and Turtle syntax too.
 
-* `ns <PREFIX>` - lookup the namespace for PREFIX
+* `rdf <PREFIX>` - lookup the namespace for PREFIX
     * `↩︎` copy entry to clipboard and paste it to front most app
     * `⌘↩` open entry in default browser
 
@@ -22,4 +24,4 @@ This workflow is inspired by the [rdf.sh](https://github.com/seebi/rdf.sh) comma
 
 The MIT License (MIT)
 
-Copyright (c) 2015 Marvin Frommhold
+Copyright (c) 2017 Marvin Frommhold