doc: update document.

Author: jaywcjlove

README.md

@@ -126,7 +126,8 @@ Currently not supported, according to the [official documentation](https://devel
 <g id="Symbols">
   <!-- A variant containing three shapes with multicolor and hierarchical annotations. -->
   <g id="Regular-M" transform="matrix(1 0 0 1 2853.78 1556)">
-      <!-- The shape is in the first multicolor layer, whose fill color is systemBlueColor. It’s also in the first layer for hierarchical rendering, and the level is primary. -->
+      <!-- The shape is in the first multicolor layer, whose fill color is systemBlueColor. 
+        It’s also in the first layer for hierarchical rendering, and the level is primary. -->
       <path class="multicolor-0:systemBlueColor hierarchical-1:primary" d="...">
 
       <!-- Two additional shapes. -->