make inheritAttrs and $attrs exception for class and style more prominent

Author: yyx990803

src/v2/api/index.md

@@ -1114,6 +1114,8 @@ if (version === 2) {
 
   By default, parent scope attribute bindings that are not recognized as props will "fallthrough" and be applied to the root element of the child component as normal HTML attributes. When authoring a component that wraps a target element or another component, this may not always be the desired behavior. By setting `inheritAttrs` to `false`, this default behavior can be disabled. The attributes are available via the `$attrs` instance property (also new in 2.4) and can be explicitly bound to a non-root element using `v-bind`.
 
+  Note: this option does **not** affect `class` and `style` bindings.
+
 ### comments
 
 > New in 2.4.0+
@@ -1312,7 +1314,7 @@ if (version === 2) {
 
 - **Details:**
 
-  Contains parent-scope attribute bindings that are not recognized (and extracted) as props. When a component doesn't have any declared props, this essentially contains all parent-scope bindings except for `class` and `style`, and can be passed down to an inner component via `v-bind="$attrs"` - useful when creating higher-order components.
+  Contains parent-scope attribute bindings (except for `class` and `style`) that are not recognized (and extracted) as props. When a component doesn't have any declared props, this essentially contains all parent-scope bindings (except for `class` and `style`), and can be passed down to an inner component via `v-bind="$attrs"` - useful when creating higher-order components.
 
 ### vm.$listeners