fixup! fix(cdk/menu): update docs to reflect current implementation and add correct role for triggers

Author: mmalerba

src/cdk/menu/menu.md

@@ -19,6 +19,40 @@ The directives in `@angular/cdk/menu` set the appropriate roles on their host el
 | CdkMenuItemCheckbox | menuitemcheckbox |
 | CdkMenuTrigger      | button           |
 
+### CSS Styles and Classes
+
+The `@angular/cdk/menu` is designed to be highly customizable to your needs. It therefore does not
+make any assumptions about how elements should be styled. You are expected to apply any required
+CSS styles, but the directives do apply CSS classes to make it easier for you to add custom styles.
+The available CSS classes are listed below, by directive.
+
+#### `cdkMenu`
+
+`cdk-menu`
+: Always applied
+`cdk-menu-inline`
+: Applied if the menu is an [inline menu](#menu-content)
+
+#### `cdkMenuBar`
+
+`cdk-menu-bar`
+: Always applied
+
+#### `cdkMenuGroup`
+
+`cdk-menu-group`
+: Always applied
+
+#### `cdkMenuItem`
+
+`cdk-menu-item`
+: Always applied
+
+#### `cdkMenuTriggerFor`
+
+`cdk-menu-trigger`
+: Always applied
+
 ### Getting started
 
 Import the `CdkMenuModule` into the `NgModule` in which you want to create menus. You can then apply
@@ -69,7 +103,7 @@ Note that Angular CDK provides no styles; you must add styles as part of buildin
 
 ### Inline Menus
 
-An _inline menu_ is a menu that lives directly on the page rather than a pop-up associated with a
+An _inline menu_ is a menu that lives directly on the page rather than in a pop-up associated with a
 trigger. You can use an inline menu when you want a persistent menu interaction on a page. Menu
 items within an inline menus are logically grouped together, and you can navigate through them
 using your keyboard. You can create an inline menu by adding the `cdkMenu` directive to the element