fix: reverted change for .attr modifier

Author: NataliaTepluhina

src/api/built-in-directives.md

@@ -319,7 +319,7 @@ Dynamically bind one or more attributes, or a component prop to an expression.
   <svg><a :xlink:special="foo"></a></svg>
   ```
 
-  The `.prop` modifier has a dedicated shorthand, `.`:
+  The `.prop` modifier also has a dedicated shorthand, `.`:
 
   ```vue-html
   <div :someProperty.prop="someObject"></div>
@@ -328,15 +328,6 @@ Dynamically bind one or more attributes, or a component prop to an expression.
   <div .someProperty="someObject"></div>
   ```
 
-  The `.attr` modifier has a shorthand `^`:
-
-  ```vue-html
-  <div :someProperty.attr="someObject"></div>
-
-  <!-- equivalent to -->
-  <div ^someProperty="someObject"></div>
-  ```
-
   The `.camel` modifier allows camelizing a `v-bind` attribute name when using in-DOM templates, e.g. the SVG `viewBox` attribute:
 
   ```vue-html