docs: variable name, not value of variable (#3224)

Update template-syntax.md

The same is the variable name rather than the value of variable.

Author: wuyuansushen

src/guide/essentials/template-syntax.md

@@ -68,7 +68,7 @@ Attributes that start with `:` may look a bit different from normal HTML, but it
 
 - Only supported in 3.4+
 
-If the attribute has the same name with the JavaScript value being bound, the syntax can be further shortened to omit the attribute value:
+If the attribute has the same name as the variable name of the JavaScript value being bound, the syntax can be further shortened to omit the attribute value:
 
 ```vue-html
 <!-- same as :id="id" -->