fix(docs): add scoped to style tags (#1620)

Author: Huangyilin19

examples/sites/demos/mobile-first/app/steps/slot-bottom.vue

@@ -59,7 +59,7 @@ export default {
 }
 </script>
 
-<style>
+<style scoped>
 /* 文本超出两行显示...，IE下不支持 */
 .multi-line {
   display: -webkit-box;

examples/sites/demos/pc/app/flowchart/basic-usage-composition-api.vue

@@ -242,7 +242,7 @@ function onClickBlank(param, e) {
 }
 </script>
 
-<style>
+<style scoped>
 /* HandlerList */
 .tiny-handler-list {
   width: calc(100% - 2px);

examples/sites/demos/pc/app/flowchart/basic-usage.vue

@@ -249,7 +249,7 @@ export default {
 }
 </script>
 
-<style>
+<style scoped>
 /* HandlerList */
 .tiny-handler-list {
   width: calc(100% - 2px);

examples/sites/demos/pc/app/time-line/shape.vue

@@ -38,7 +38,7 @@ export default {
 }
 </script>
 
-<style>
+<style scoped>
 .tiny-button {
   margin-bottom: 24px;
 }

examples/sites/demos/pc/app/time-line/status.vue

@@ -44,7 +44,7 @@ export default {
 }
 </script>
 
-<style>
+<style scoped>
 code {
   color: #476582;
   padding: 2px 8px;