docs(*): use @description instead of @returns for properties

Dgeni-packages was not actually rendering the `@returns` text.

Closes #8639

Author: shahata

src/loader.js

@@ -114,7 +114,7 @@ function setupModuleLoader(window) {
            * @ngdoc property
            * @name angular.Module#requires
            * @module ng
-           * @returns {Array.<string>} List of module names which must be loaded before this module.
+           *
            * @description
            * Holds the list of modules which the injector will load before the current module is
            * loaded.
@@ -125,8 +125,9 @@ function setupModuleLoader(window) {
            * @ngdoc property
            * @name angular.Module#name
            * @module ng
-           * @returns {string} Name of the module.
+           *
            * @description
+           * Name of the module.
            */
           name: name,
 

src/ng/compile.js

@@ -2011,8 +2011,10 @@ function directiveNormalize(name) {
 /**
  * @ngdoc property
  * @name $compile.directive.Attributes#$attr
- * @returns {object} A map of DOM element attribute names to the normalized name. This is
- *                   needed to do reverse lookup from normalized name back to actual name.
+ *
+ * @description
+ * A map of DOM element attribute names to the normalized name. This is
+ * needed to do reverse lookup from normalized name back to actual name.
  */