Fix namespaced bug with nav items generated (ember-learn#379)

Author: alexmaingot-sf

lib/broccoli/docs-compiler/navigation-index-generator.js

@@ -52,12 +52,20 @@ module.exports = class NavigationIndexGenerator {
     return resolvedType || 'modules';
   }
 
-  _resolvedTypeForModule(module) {
-    let [ , type ] = module.file.split('/');
+_resolvedTypeForModule(module) {
+  let path = module.file.split('/');
 
-    return RESOLVED_TYPES.includes(type) && type;
+  // By default we assume that the type is at index 1
+  let type = path[1];
+
+  // If the module is a scoped package, then the type will be at index 2
+  if (path[0].charAt(0) === '@') {
+    type = path[2];
   }
 
+  return RESOLVED_TYPES.includes(type) && type;
+}
+
   _isResolvedType(module) {
     return this._resolvedTypeForModule(module);
   }