docs($route): add missing error document

Author: petebacondarwin

docs/content/error/$route/norout.ngdoc

@@ -0,0 +1,8 @@
+@ngdoc error
+@name $route:norout
+@fullName Tried updating route when with no current route
+@description
+
+Occurs when an attempt is made to update the parameters on the current route when
+there is no current route. This can happen if you try to call `$route.updateParams();`
+before the first route transition has completed.