doc(label): fix label rich style does not inherit the plain label style

apache/echarts#20977

Author: Ovilia

en/option/partial/text-style.md

@@ -111,7 +111,9 @@ For more details, see [Rich Text](tutorial.html#Rich%20Text) please.
 ) }}
 {{ /if }}
 
+#${prefix} richInheritPlainLabel(boolean) = true
 
+Whether rich text inherits plain text style.
 
 {{ target: partial-text-style-base-item }}
 

zh/option/partial/text-style.md

@@ -111,7 +111,9 @@ label: {
 ) }}
 {{ /if }}
 
+#${prefix} richInheritPlainLabel(boolean) = true
 
+富文本样式是否继承普通文本样式。
 
 {{ target: partial-text-style-base-item }}