docs: update docs

Author: zhensherlock

docs/zh/guide/watermark.md

@@ -20,22 +20,6 @@ const app = getCurrentInstance();
 let childElementWatermark = null
 
 onMounted(() => {
-  // 富文本水印
-  richTextWatermark = new Watermark({
-    contentType: 'rich-text',
-    content: '<div style="background: #ccc;">富文本水印 <span style="color: #f00">good</span></div>',
-    width: 300,
-    height: 300,
-    filter: 'blur(2px)',
-    movable: true,
-    onSuccess: () => {
-      app.appContext.config.globalProperties.$message({
-        appendTo: '#app',
-        message: '富文本水印添加成功！',
-        type: 'success'
-      });
-    }
-  });
   // 子元素水印
   childElementWatermark = new Watermark({
     parent: '.parent-element',
@@ -342,7 +326,10 @@ watermark.create() // 添加水印
 
 watermark.destroy() // 删除水印
 ```
-<div class="parent-element" style="width: 400px;height: 400px;border: 1px solid #333;margin-top: 10px;position: relative;">
+<div class="parent-element" style="border: 1px solid #333;width: 400px;height: 400px;margin-top: 10px;position: relative;overflow: hidden;">
+  <div class="scroll-list" style="overflow: auto;width: 400px;height: 400px;">
+    <div v-for="(item, index) in Array.from({length: 100})">{{index + 1}}</div>
+  </div>
 </div>
 <el-affix target=".child-element-watermark" position="bottom" :offset="0" z-index="1000">
   <el-space class="block-operation">