Update license name

Author: yurrriq

src/elli_websocket.app.src

@@ -7,7 +7,7 @@
   {env,          []},
 
   {maintainers,  ["elli-lib team"]},
-  {licenses,     ["Apache"]},
+  {licenses,     ["Apache 2.0"]},
   {links, [
     {"GitHub", "https://github.com/elli-lib/elli_websocket"}
   ]}