pref: 调整插件目录，增加一些帮助说明

packages/plugins/plugin-tencent/src/index.ts

@@ -1,3 +0,0 @@
-export * from "./access";
-export * from "./plugin";
-export * from "./dns-provider";

packages/ui/certd-server/src/plugins/plugin-tencent/index.ts

@@ -0,0 +1,3 @@
+export * from './access';
+export * from './plugin';
+export * from './dns-provider';